various species of plants and animals, instead of being each specially created and immutable, are continually undergoing modification and change through a process of adaptation, by virtue of which such varieties of the species as are in any way better fitted for the rough work of the struggle for existence are enabled to survive and multiply at the expense of the others. Mr. Darwin considers this principle, with, indeed, some other and less important causes, capable of explaining the manner in which all existing types may have descended from one or a very few low forms of life. All animals, beasts, birds, reptiles, insects have descended, he contends, from a very limited number of progenitors, and he holds that analogy points to the belief that all animals and plants whatever have descended from one common prototype. The idea that man gradually developed from some very low prototype was, of course, not Dr. Darwin's especially, nor belonging even to Dr. Darwin's time. It was an idea that had been floating about the world almost at all times. It had become somewhat fashionable in England not long before Dr. Darwin published his "Origin of Species." It was led up to in the "Vestiges of Creation," a book that once caused much stir in scientific and religious circles. A strong-minded lady in Lord Beaconsfield's "Tancred" bewilders and saddens the young hero by gravely informing him that we once were fishes, and shall probably in the end be crows. But Darwin's book, if we take it as resting for its central point of doctrine upon that principle of the fittest, was the first great systematized attempt to give the theory a solid place among the scientific opinions of the world. It was worked out with the most minute and elaborate care, and with an inexhaustible patience--qualities which we do not expect to find in the originators of new and startling theories. Dr. Darwin's work was fiercely assailed and passionately championed. It was not the scientific principle which inflamed so much commotion; it

was the supposed bearing of the doctrines on revealed religion. Injustice was done to the calm examination of Darwin's theory on both sides of the controversy. Many who really had not yet given themselves time even to consider its arguments cried out in admiration of the book, merely because they assumed that it was destined to deal a blow to the faith in revealed religion. On the other side, many of the believers in revealed religion were much too easily alarmed and too sensitive. Many of them did not pause to ask themselves whether, if every article of the doctrine were proved to be scientifically true, it would affect in the slightest degree the basis of their religious faith. To this writer it seems clear that Dr. Darwin's theory might be accepted by the most orthodox believer without the firmness of his faith moulting a feather. The theory is one altogether as to the process of growth and construction in the universe, and whether accurate or inaccurate, does not seem in any wise to touch the question which is concerned with the sources of all life, movement, and being. However that may be, it is certain that the book made an era not only in science, but in scientific controversy, and not merely in scientific controversy, but in controversy expanding into all circles and among all intelligences. The scholar and the fribble, the divine and the school-girl, still talk and argue and wrangle over Darwin and the origin of species.

Professor Huxley is one of the most distinguished and thoroughgoing supporters of Dr. Darwin's principle. Professor Huxley advocates, in his own words, "the hypothesis which supposes that species living at any time must be the result of a gradual modification of pre-existing species." He maintains that to suppose each species of plant or animal to have been formed and placed on the globe at long intervals by a distinct action of creative power, is an assumption "as unsupported by tradition or revelation as it is opposed to the general analogy of nature." Professor

Huxley would have been a distinguished scientific man if he had never taken any part in the Darwin controversy. He would have been a distinguished scientific man even if he had not been, as he is, a great thinker and writer. In the arena of public controversy he has long been a familiar and formidable figure. He came into the field at first almost unknown, like the Disinherited Knight in Scott's romance; and while the good-natured spectators were urging him to turn the blunt end of the lance against the shield of the least formidable opponent, he dashed, with splendid recklessness and with spear-point forward, against the buckler of Richard Owen himself, then the most renowned of England's living naturalists. Professor Huxley has a happy gift of shrewd sense and sarcasm combined. Few men can expose a sophism so effectively in a single sentence of exhaustive satire. It would be wrong to regard him merely as a scientific man. He is a literary man as well. What he writes would be worth reading for its form and its expression alone, were it of no scientific authority. He has a fascinating style, and a happy way of pressing into the service of strictly scientific exposition some illustration caught from literature and art, even from popular and light literature. Mr. Huxley seemed from the first to understand that a scientific school can never become really powerful while it is content with the ear of strictly scientific men. He cultivated, therefore, sedulously and successfully, the literary art of expression. His style as a lecturer has a special charm. It is free from any effort at rhetorical eloquence; but it has all the eloquence which is born of the union of deep thought with simple expression and luminous diction. There is not much of the poetic about Mr. Huxley's style; but the occasional vividness of his illustrations suggests the existence of some of the higher imaginative qualities. There was something like a gleam of the poetic in the half-melancholy, half-humorous introduction of Balzac's famous "Peau de

But, as

Chagrin" into the well-known protoplasm lecture. a rule, Mr. Huxley treads only the firm earth, and deliberately, perhaps scornfully, rejects any aspirings after the clouds.

Professor Tyndall, another great teacher in the same school, has, like Mr. Huxley, the gift of literary expression, informed, perhaps, by more of the imaginative and the poetic. Mr. Tyndall has done, perhaps, more practical work in science than Mr. Huxley. He has written more; he has sometimes written more eloquently. But there is a certain coarseness of materialism about Mr. Tyndall's views with regard to man and nature. There is a vehement aggressiveness in him which must interfere with the clearness of his views. He has occasionally assailed the orthodox with the polemical intemperance of a field-preacher. He has more than once been carried clear away from his purpose by the unsparing vigor of his controversial style. He is sometimes one of the most impatient of sages, the most intolerant of philosophers. His temper as a controversialist may have tended sometimes to weaken his scientific authority, but of course this only happens where the subject engrossing Professor Tyndall's attention is one of that class which have in all ages proved too exciting now and then for the cool judgment even of philosophers. Mr. Tyndall has made noble contributions to scientific literature which concern in no wise the tremendous questions put by Mr. Carlyle, with such solemnity and such emotion "Whence, and, oh heavens! whither?"

Mr. Herbert Spencer may be said to have taken the sphere of the naturalist and the spheres of the metaphysician and the psychologist, and drawn a circle round, embracing and enfolding them all, and adopting them as his province. If Mr. Darwin's attempt to map out the process by which vegetable and animal life are gradually constructed was an ambitious effort, the task which Mr. Herbert Spencer

undertook was of still more vast and venturous scope. Mr. Spencer is the author of a series of connected philosophical works intended to reduce to harmonious and scientific order the principles of biology, psychology, sociology, and moraJity. He has applied universally, and carried out in systematic detail the doctrine of evolution or development. In 1855 appeared his "Principles of Psychology," an attempt to analyze the relations between the order of the worlds of matter and of mind. The central and governing idea of this work is that the universal law of intelligence flows directly from the co-operation of mind and nature, in the creation of our ideas. As there is a persistency in the order of events in nature, so will there be a persistency in the connection between the corresponding states of consciousness. The succession or co-existence of external phenomena produces a like succession in our mental perceptions, and when any two physical states ofter occur together, there is at length established an internal tendency for those states always to recur in the same order. Starting from the law which has been thus described in words that are not ours, Mr. Spencer traces the growth of human intelligence from the lower phenomena of reflex action and instinct, and then shows how our unconscious lite merges in a succession of conscious phenomena; and lastly, he endeavors to carry us upward from the origin of memory to the highest exercise of reason and the scientific development of the moral feelings. In other words, Mr. Spencer endeavors to lay down the principles of development for the whole world of matter, of mind, and of morals. Mr. Spencer has written essays on education, on the government of states, and on other subjects, which, however, scarcely seem to be marked by the precision of thought which distinguishes him as a psychological writer. His views of education and of civic government seem occasionally to degenerate almost to the degree of crotchets. His style is not fascinating. It is clear, strong,