Readers of Buckle will remember the startling contrasts he draws between the Scotland of the seventeenth and eighteenth centuries. According to Buckle, in the seventeenth century the Scottish clergy kept the people in a state of intellectual bondage; in the eighteenth century, thanks to men such as Hutcheson, Hume, and Adam Smith, the chains which kept the people in bondage were broken, and the country entered upon a glorious career of intellectual freedom and discovery. It is remarkable that Buckle, who professed a high regard for science, should have approached the history of Scotland in a woefully unscientific spirit. The History of Civilization had great vogue in its day, and even yet it may be read with profit by those who like to have facts presented in the form of luminous generalizations. Tried by modern standards, Buckle's book, however, is found wanting, and that simply because the author, in approaching the study of history, entirely ignored the great principle of relativity, which plays such an important part in the interpretation of the past. National institutions are no longer judged by absolute standards; they are studied in relation to their historical environments and estimated accordingly. Institutions which, tried by modern standards, are condemned as obstructions to progress may find their explanation and justification in the fact that they were the natural and necessary products of the time in which they flourished. Attention to the idea of relativity, which we owe to the evolution conception of history, would save modern disciples of Buckle from a partisan attitude towards Scottish history. Certain writers, for instance, are never weary of representing the Reformation as the substitution of one kind of despotism for another— the despotism of Presbyterianism for the despotism of Romanism. Thus it has come about that writers who have no sympathy with the great religious movements of Scotland contrast the turbulence and wranglings of the sixteenth and seventeenth centuries with the comparative calm of the eighteenth century, and in a tone of contempt discuss the centuries of religious struggle as a kind of prolonged Donnybrook. A deep study of Scottish history shows that there is no such gulf as Buckle represents between the seventeenth and eighteenth centuries. The antagonism lies on the surface. When viewed calmly and rationally, it will be found that the seventeenth was the natural preparation for the eighteenth century—that, in other words, the struggle for religious liberty under the Reformers and the Covenanters was the necessary preparation for the scientific movement. What the Reformers and the Covenanters did was to secure liberty, without which the cultivation of science was impossible. We see an illustration of this in the case of Napier of Merchiston. He founded no school. Why? As I have remarked elsewhere—

"The explanation is not far to seek. After James VI ascended the throne of England in 1603, the trouble between the king and his Presbyterian subjects, which had long been brewing, grew steadily worse. With England at his back, James resumed with renewed energy his efforts to anglicize the Church of Scotland—efforts which were continued by his son and grandson. In the end the kings were defeated, and Scotland retained her national religion; but they were not defeated without a terrible struggle and a terrible sacrifice. The best minds of the nation were absorbed in the struggle, and there was no time for scientific research. The Covenanters, it is true, did not view scientific research with a friendly eye, but it is unjust to blame them for the neglect of science in Scotland. The times were unsettled; and when men were being shot down at their own doors, and sent as prisoners to the Bass Rock and Dunnottar, it was not to be expected that science could gain a footing."

When the Reformers and the Covenanters won the battle for religious liberty, when they secured for Scotland spiritual independence, they paved the way for the enjoyment of intellectual independence, without which scientific research is impossible. Unknown to one another, the men of religion, the men of letters, and the men of science were fighting as soldiers in the same great cause of emancipation. In the evolution of Scottish life and thought the seventeenth century was a factor on the side of progress, and not, as Buckle thought, an obstructive force. The blood of the martyr proved to be the seed of the State as well as of the Church.

That it was the disturbed state of the country and not intellectual inaptitude that was the cause of Scotland's intellectual backwardness was conclusively shown by the quickness with which the national mind fell into line with the great scientific movement associated with Isaac Newton. The improvement was retarded at the outset by the confused notions held by leading thinkers with regard to scientific method. The tendency, which may be traced in Descartes, was to mix two things essentially different, namely, scientific descriptions of the Universe with philosophical explanations. Whereas Descartes, for example, not content with the discovery of facts and their classification was always introducing metaphysical elements, Newton carefully distinguished between the mechanical forces with which he had to deal, and their spiritual interpretation. From a metaphysical conception of Matter Descartes formulated certain views which, as they could not be verified, were of no real scientific value. Newton, on the other hand, laid supreme stress upon verification. Take his handling of Gravitation. Attraction and repulsion were favourite metaphysical phrases, but they had no practical value till Newton formulated in exact language his famous discovery. As George Henry Lewes says, a theory may be transferred from science to metaphysics by withdrawing the verifiable element. Withdraw the formula inversely as the square of the distance, and directly as the mass, and attraction is left a mere occult quality. It was precisely because Newton stood faithfully upon verification and demonstrable fact that even in France he was recognized in preference to Descartes as the founder of modern science.

The positive and logical cast of the Scottish mind at once detected the significance of Newton's system: in fact, Scotland was far ahead of England in recognizing the great scientific value of Newton's work; as evidence of this is the fact that his system was taught in Edinburgh University thirty-five years before it was recognized in Newton's own university of Cambridge. Buckle credits the Scottish mind with a strong aptitude towards the deductive method in the search for truth, and he seems to have justification for this view in the remarkable success of the early scientists in the sphere of mathematics—a fact which goes far to explain the popularity of the Newtonian system in the Scottish universities. Further evidence of the aptitude of the Scottish mind for scientific study is had in the fact that in the distracted sixteenth century, in the midst of social and ecclesiastical turmoil, there sprang up a man who has left his mark upon the science of mathematics—namely, Napier of Merchiston, the inventor of logarithms. As has been well said, "whether we consider the great originality of the idea, the difficulty of carrying it into effect in the state in which algebraical analysis then was, or the immense practical and theoretical value of the invention, we shall have little difficulty in claiming for Napier the honour of a discovery unsurpassed in brilliancy in the whole history of mathematics."

Colin Maclaurin, who succeeded David Gregory, the introducer of Newton's system into Scotland, was a mathematical genius of the first order, and gave enthusiastic reception to the doctrines of Newton. His Memoir on the Tides, written from the standpoint of the gravitation theory, gained equal honour with Euler and Daniel Bernoulli, a famous Italian mathematician, the prize of the French Academy being equally divided among them. Referring to the part which Maclaurin played in planting the germs of scientific thought in Scotland, Professor Playfair, writing in the second volume of the Edinburgh Review, says, " the teaching of science by Maclaurin in Edinburgh University surpassed probably at that time the teaching of any other English or Continental university."

The close connection between spiritual and intellectual liberty is seen in the stamp of progressiveness which the Scottish universities got at the Reformation. From the writings of Buckle one would infer that the whole weight of the Reformed Church was thrown on the side of obscurantism; whereas, as a matter of fact, the universities bore the impress of the great educational movement associated with the revolt against Rome. On this point Dr. Merz, in his valuable work on European thought in the nineteenth century, referring to the Scottish universities, notes the close connection between the educational movement and the Reformation, and in the course of a contrast between them and the English universities, says—

"The universities of Scotland, unlike those of England, instead of nursing an exclusive spirit and encouraging only scanty intercourse between teachers and students of different centres, lived in constant exchange of professors and ideas, much in the same way as has always been the custom, on a larger scale, among German and other Continental universities. Though this is destructive of that individual character of the university or the college which is so highly prized by many English fellows, it is certainly more conducive to the progress of studies and research, and it is the cause why, in the early history of recent science, the universities of Scotland have played so much more important a part than those of England."

After the Union, when the political and ecclesiastical storms had spent their force, Scotland set herself diligently to cultivate the things that make for a pacific and progressive civilization. The heroes of the Reformation and Covenanting times had accomplished the great task of establishing the liberties of Scotland on a firm basis, and it now remained for the thinkers of the eighteenth century to build upon the foundation that had been laid in blood. It must be admitted that in their attitude to the new spirit and the new conditions the clergy were not equal to the occasion. They strove to keep the universities as nurseries to the Church. When, in 1639, the Covenanters gained the ascendency, they passed a resolution that all masters and teachers of colleges and schools should subscribe to the Covenant. Special care was taken that all the universities, and more especially the chairs of Divinity, should be filled by those favourable to the Reformed doctrines. Indeed, after the Revolution, subscription to the Confession of Faith was made a condition of holding office in the universities. Such short-sighted regulations did much to increase the unpopularity of the Church among thinking men, and considerably retarded the progress of the scientific movement. Still, with all their drawbacks, the Scottish universities were more favourable to the cultivation of science than those of England. As Dr. Merz says—

"Whilst in England modern science was cultivated outside the pale of the universities by Priestly, Davy, Wollaston, Young, Dalton, Faraday, and Joule—to whom we may even add Green and Boole—all eminent Scotch men of science, such as Gregory, Simson, Maclaurin, Playfair, Black, Thomson, Leslie, Brewster, and Forbes, were university professors, many of whom did not confine their labours to one centre, but spread the light of their ideas and researches all over the country. Whilst England has been great in single names, Scotland has certainly in proportion done more to diffuse modern scientific knowledge."

Newton's epoch-making discovery naturally directed attention to Astronomy. Now that the law of planetary movements had been found the minds of leading thinkers became agitated over the problem of the origin of the Solar system. Was it possible not only to explain by gravitation the sublime harmony of the Solar system, but also its origin and development ? The answer came in the shape of the Nebular theory. To Kant is assigned the credit of the theory, but it is not generally known that before Kant, James Ferguson, the Scottish astronomer, anticipated the German philosopher. Ferguson held that the matter now forming the sun and planets originally existed in a detached condition through space, and by the force of gravitation were drawn together to form the celestial bodies. Contemporary with Ferguson was Alexander Wilson, the first director of the Glasgow Observatory, of whose services to science too little has been written. He was the virtual founder of the scientific study of the sun, and the first to make an exhaustive study of sun spots. He was the first of the Glasgow school of astronomers to treat meteorology on scientific principles.

The honourable place which Scotland held in the eighteenth she continued to hold in the nineteenth century. In the science of astronomy Scotland was well to the front. Thomas Henderson, born in 1798, was one of the most famous astronomers of his age. He was the first to measure the distance of the stars, and thus solved a problem which had baffled the greatest men of science from Galileo to Herschel. Contemporary with Henderson at Edinburgh was John Pringle Nichol, Glasgow University. As an observer Nichol ranked far below Henderson, but constructive thinker he ranked above him. His work in defending the Nebular hypothesis when most of the great men of science had abandoned it can never be forgotten. On his death in 1859 he was succeeded by Robert Grant, whose History of Physical Astronomy is a standard work to this day. Mention should also be made of Sir David Gill, of Aberdeen, whose work practical astronomer has gained for him an enduring reputation.

The Nebular theory started the scientific mind on a new track. The idea of seeking the origin of the Solar system in a highly diffused gaseous matter raised questions with regard to the nature of matter. Whether or not it be as the result of centuries of intellectual dialectics it is a curious fact that the Scottish mind has always shown a marked fondness for the abstruse departments of knowledge. At any rate Scottish scientists have taken a special interest in matter, its nature and constitution. In this department they have done excellent pioneering work; indeed it may be claimed for an eighteenth-century scientist, Joseph Black, the credit, by his investigations into the nature of heat, of putting scientists on the track of the modern doctrine of the indestructibility and transformation of force. Modern science is now familiar with the conception that the forces of Nature—such as heat, light, electricity, etc.—which used to be treated as independent entities are simply temporary manifestations of one form of energy which in its totality is incapable of increase or decrease. At the time of Black, heat was supposed to be a separate distinct material agent, though Bacon in his quaint prophetic way ventured to speak of it as a mode of motion. By his discovery of what is known as latent heat Black struck a blow at the material theory, though it must be admitted he did not see the full issues of his own discovery. He clung to the old view that heat was a material substance; but his discovery paved the way for further discoveries by his successors which led to the important conclusion that heat and light are identical, and are capable of translation into each other.

If heat is shown to be simply a mode of motion, and no material entity, might not the same thing be said of other forms of force? Experiment verified the supposition, and thus, from Black's investigations into the nature of heat, the scientific mind proceeded till it was able to formulate the law of the mechanical equivalent of heat which has since become the corner-stone of the far-reaching law of the conservation of energy. As showing the close connection between speculative and practical science, it is interesting to note that in course of his labours in connection with the steam-engine, James Watt was greatly aided by the latent heat theory of Black.

Following Black came Sir John Leslie, who, in addition to his contributions to the study of heat and light, anticipated what is now known as the evolutionary view of Nature. At a time when Nature was treated on the department system, when each part was supposed to have been specially created, we find Leslie writing as follows: "We should recollect that in all her productions Nature exhibits a chain of perpetual gradations, and that the systematic divisions and limitations are entirely artificial, and designed merely to assist the memory and facilitate our conceptions." The idea which Darwin and Spencer have popularized in our day is to be found in the writings of Leslie—the idea of the continuity of Nature. Nay, further, we find Leslie venturing into a region which even in our advanced days is dark and mysterious. There are those who would extend the idea of life not merely to organic, but to inorganic matter. The distinction between living and dead matter, it is said, is not true to the nature of things. Says Leslie: "All forces are radically of the same kind, and the distinction of them into living and dead is not grounded on just principles." In a strain remarkably anticipatory of modern scientific speculation, we find Leslie saying that even dead or inorganic substances must in their recondite arrangements exert such varying energies as, if fully unveiled to our eyes, could not fail to strike us with wonder and surprise.

On the death of Leslie he was succeeded in the Chair of Natural Philosophy, in 1833, by James David Forbes, who permanently linked his name to science by his important demonstration of the polarization of heat. In addition he made valuable researches on the conduction of heat by iron bars, and underground temperature. His name will be most intimately associated with his important investigations into the nature of glaciers and glacial motion. In the department of Physics another Scottish scientist holds high place, Sir David Brewster, by his discoveries in light and especially with regard to its polarization. In the words of the late Professor Tait, to Brewster are due all the most important results arrived at in the field of optics during the nineteenth century. Brewster's position in science has been thus described by Forbes, his friend and fellow-labourer in the same field: "Few persons have made with their own eyes so vast a number of important observations; few have ever observed better or recorded their observations more faithfully. His scientific glory is different from that of Young and Fresnel, but the discoverer of the law of polarization, of biaxal crystals, of optical mineralogy and of double refraction by compression will always occupy a foremost rank in the intellectual history of the age." The line of research started by Black and Leslie, and continued by Forbes and Brewster, was pursued by James Clerk-Maxwell, the late Lord Kelvin, and the late Professor Tait.

In the sphere of what may be called transcendental physics—that dealing with the nature and constitution of matter—the Scottish school of scientists are in the foremost rank. This is admitted by the author of European Thought in the Nineteenth Century as follows: "The important task of rebuilding the edifice of the physical sciences, and establishing it on a large scale, fell almost exclusively into the hands of what we may call the Scottish school of natural philosophy—James and William Thomson, Macquorn Rankine, James Clerk-Maxwell, and Balfour Stewart in this country, whilst Clausius worked abroad almost alone." In the same connection is the following testimony by the same author :—

"The real compendium of the new doctrine is the treatise on natural philosophy by Thomson (Lord Kelvin) and Tait, which has probably done more than any other book in this country to lead the mathematical students at the foremost universities and colleges into paths more useful for physical and experimental research. The greatest exponent of the new ideas was James Clerk-Maxwell, to whom is also due the merit of having applied them for the purpose of testing and confirming the worth of the treasure which lay hidden in the experimental researches of Faraday. Next to the handbook of Thomson and Tait no writings probably have done more—especially outside of England, on the Continent and in America— than those of Maxwell to revolutionize the teaching of natural philosophy."

What, then, was the revolution in the scientific conception of the nature and constitution of matter caused by the Scottish school?

The germ of the revolution was the kinetic theory of gases so brilliantly associated with the name of Clerk-Maxwell. Up till then men of science accepted the Newtonian conception of matter as being made of solid hard particles —so very hard, in the words of Newton, "as never to wear or break in pieces; no ordinary power was able to divide what God Himself made one in the first creation." Here in substance was the atomic theory of matter. This, which is known as the mechanical theory, got a severe blow when Joule showed that heat, for instance, was not a property of matter but a mode of motion. If heat is not a form of matter, but a mode of motion, might not the same thing be said of other so-called properties of matter—light, electricity, magnetism? What if it should be found that all the so-called properties of matter are simply modes of motion?

From this it was just a step to the doctrine of the conservation and the convertibility of force, or, as it is now called, energy—a doctrine which was placed on a scientific basis when Joule discovered the dynamical equivalent of heat. The investigations of Clerk-Maxwell, Helmholtz, and Hertz had the effect of substituting the dynamical for the mechanical theory of matter, and though Lord Kelvin was slow in accepting the new views, when he did accept them he worked incessantly at the idea of "a great chart in which all physical science will be represented with every property of matter shown in dynamic relation to the whole." The atom, which formerly was viewed as a hard, indestructible substance, now began to be conceived as a centre of energy, more particularly when, by his investigations into the electro-magnetic theory of light, Clerk-Maxwell was led to the conclusion that we were not dealing with properties of matter, but with undulations or vibrations of energy in a uniform medium. What is this medium? It is called the ether; and it was at this point that Kelvin made the boldest and most far-reaching attempt that has ever been made to solve the problem of the nature and constitution of matter. By his famous vortex ring theory he sought to show how matter itself might be evolved from the ether. Kelvin himself was not satisfied with the theory, but a competent authority like Professor J. J. Thomson—who in this department of physics is doing splendid work—regards "the vortex atom explanation as the goal at which to aim."

To recent speculation about radium and electrons Lord Kelvin was not quite sympathetic. His mind, naturally conservative, was slow to move except under the compulsion of demonstrative fact. What he aimed at was to reduce all physical phenomena within the duality of matter and energy. To this he added ether and electricity, but the recent extraordinary discoveries in regard to matter make it plain that the time is not yet for a great comprehensive theory which will unify the marvellous play of forces which we call the material universe.

The researches of Clerk-Maxwell have been in the highest degree fruitful. His electromagnetic theory of light has been pronounced as one of the most unifying ideas in modern science. In the department of electricity Maxwell's influence has been thus defined by Professor Arthur Thomson—one of Scotland's rising scientists. "The scientific study of electricity initiated by Oersted and Ampere was profoundly influenced by the experimental genius and scientific temper of Faraday, found mathematical or precise formulation in the work of Lord Kelvin, and was developed into a provisional dynamical theory by the extraordinary insight of Clerk-Maxwell. It is perhaps not too much to say that what Newton did for gravitational phenomena was done by Clerk-Maxwell for electrical phenomena."

Thus it has come to pass that largely to the investigations of the Scottish school into the nature of electricity the conception of the atom which used to be viewed as the imperishable foundation-stone of the Universe has been completely revolutionized. Later researches, indeed, go to show that the atom is not an ultimate, but composed of corpuscles of which it is calculated that five hundred go to make an atom of hydrogen. It seems as if at the end of our scientific explanations we were brought face to face with the view that in its last analysis, viewed dynamically, Matter with its mysterious potencies is the manifestation of what Spencer calls the Infinite and Eternal Energy, personified by Goethe—