Some of the most noted leaders of thought in our own era were likewise chronic invalids. Among these were the scholarly theologian, E. B. Pusey, and J. A. Symonds, the historian of the Renaissance. There was also Herbert Spencer, who was frequently forced by nervous breakdowns to take long periods of absolute rest. More remarkable still was the case of the famous naturalist, Charles Darwin. "It is," writes his son, "a principal feature of his life that for nearly forty years he never knew one day of the health of ordinary men, and that thus his life was one long struggle against the weariness and the strain of sickness."[94] But, notwithstanding his continued ill health and the spinal anemia from which he suffered, he was able to conduct those epoch-making researches which put him in the forefront of men of science, and to write those famous books which have completely revolutionized our views of nature and nature's laws.

But a still more remarkable illustration of the fact that there is no necessary relation between muscular and mental power, between physical well-being and intellectual energy, is afforded by the illustrious discoverer of the world of the infinitely little, Louis Pasteur. Stricken by hemiplegia shortly after he had begun those brilliant investigations which have rendered him immortal, he remained affected by partial paralysis until the end of his life. His friends had reason to fear that this attack, even if he should survive it, would weaken or extinguish his spirit of initiative, if it did not make further work entirely impossible. But this was far from the case. For a quarter of a century he continued with unabated activity those marvelous labors which are forever associated with his name. And it was after, not before, his misfortune that he made his most famous discoveries in the domain of microbian life, and placed in the hands of physicians and surgeons those infallible means of combatting disease which have made him one of the greatest benefactors of suffering humanity. The complete separation of the intellectual from the motor faculties was never more clearly exhibited than in this case, nor was it ever more completely demonstrated by an experiment, whose validity no one could question, that power of mind does not necessarily depend on strength or health of body. It proved, also, in the most telling manner that it is not muscular but psychic force which avails most, whether to the individual or to society. And it showed, at the same time, the utter absurdity of those theories which would fatally connect intellectual with physical debility in woman, and would forever adjudge the physically weaker sex to be of hopeless inferiority in all things of the mind.

What has been said of men achieving renown, notwithstanding ill health, may likewise be affirmed of women. The case of Elizabeth Barrett Browning is scarcely less remarkable than that of Darwin. In spite of being a chronic invalid the greater part of her life, she attained a position in letters reached by but few of her contemporaries. The same almost may be said of the three Brontë sisters. The deadly seeds of consumption were sown in their systems in early youth, but, although fully aware that life had "passed them by with averted head," they were, through their indomitable wills, able to send forth from their bleak home in the wild Yorkshire moors works of genius that still instruct and delight the world.

From the foregoing it is clear that valetudinarianism, if it prove anything, proves not that it renders intellectual effort impossible, but that it serves as a discipline for the soul. It forces the mind to husband its strength, and thus enables it to accomplish by economy and concentration of effort that which the same mind in a healthy body, with the distractions of society and the allurements of life, would be unable to accomplish. It exemplifies in the most striking manner the truth of what Socrates says in Plato's Republic about the beneficent action of the "bridle of Theages," preventing an infirm friend of his from embracing politics and keeping him true to his first love—philosophy.

Failing to show any necessary connection between superior physique and intellectual capacity, between health of body and mental activity, between the amount of food consumed and the degree of intelligence, the class of thinkers whose theories are now under consideration found themselves forced to abandon the argument based on robust health and physical strength and seek elsewhere for support of their views. This, they soon announced, was found in the greater cranial capacity and greater brain weight of the male as compared with that of the female. Following up this fancied clew, anthropologists the world over began measuring skulls and weighing brains in order to determine the supposed ratio of sex-difference.

The results of these investigations were far from corroborating the preconceived notions of those who had fancied a necessary correlation between mental capacity and size of cranium, between the weight of encephalon and degree of intelligence. For it was soon discovered that cranial capacity depended on many causes—many of them unknown—and that people having the largest skulls were often far from being the ones dowered with the greatest intellectual power. It was found, for instance, that climate was a determining factor—that the inhabitants of northern regions have larger heads than those who live farther south. Thus the Lapps, in proportion to their stature, have the largest heads in Europe. After these come in order the Scandinavians, the Germans, the French, the Italians, the Arabs.

It was found also that the least cranial capacity of the ancient Egyptians coincides with the most brilliant period of their civilization—that of the eighteenth dynasty. Measurements of skulls unearthed at Pompeii showed that the heads of the Romans who lived two thousand years ago were larger than the heads of the Romans of to-day. Similarly, the skulls of the lake-dwellers of Switzerland were larger than those of the Swiss people of the present time, while the average circumference of the skulls measured in the catacombs of Paris is more than an inch greater than that of the Parisians who have died during the last half century. The circumference of the skulls of a large number of mound-builders, excavated some years ago near Carrollton, Illinois, exceeded that of the average head of white men in New York of our day by nearly three inches. This shows that the culture of the white race during long centuries has not developed its cranial capacity to equal that of the uncultured Indians who flourished in the Mississippi valley untold generations ago.

The skulls of Quaternary men were likewise very voluminous, although they belonged to a race whose mental manifestations were infantile in the extreme. Even the celebrated Engis skull, one of the most ancient in existence, has been described by the late Professor Huxley as well formed and considerably larger than the average of the European skulls of to-day, not only in the width and height of the forehead, but also in the cubic capacity of the whole. Furthermore, the eminent craniologist, Broca, has proved that the illiterate peasants of Auvergne have a much greater cranial capacity than that of the learned and cultured denizens of Paris. And, as if to show conclusively that there is no necessary connection between intellectual capacity and size of cranium, authentic measurements disclose the fact that some of the most gifted men the world has known had small heads. Among these were Dante and Voltaire. The skull of the latter is one of the smallest which has thus far been observed.

What has been said regarding the relation of cranial volume to intellectual capacity, as revealed by the measurements of the skulls of ancient and modern, savage and civilized peoples may likewise be predicated of the differences in the sizes of the crania of men and women. No argument as to the greater or less intelligence of either sex can be based on mere craniometric determinations. "At the best, cranial capacity is but a rough indication of brain size; and to measure brain size by the external size of the skull furnishes still rougher and more fallacious approximations, since the male skull is more massive than the female."

Even the slight morphological differences between male and female skulls—some anthropologists deny that there are any at all—afford no more ground for conclusions in favor of the superiority of one or the other sex than the relative differences in size. Such trifling differences as do exist exhibit, as Virchow has pointed out, an approximation of men to the savage, simian and senile type, and an approach of women to the infantile type. Havelock Ellis, commenting on this difference, pertinently remarks, "It is open to a man in a Pharisaic mood to thank God that his cranial type is far removed from the infantile. It is equally open to woman in such a mood to be thankful that her cranial type does not approach the senile."[95]