Apart from what is found in the works of Aristotle, the biology of the ancients was medicine. The medicine, for a thousand years of our era, was that of the second century Greek physician Galen, a healer who was ignorant of even the correct number and placement of the bones of the human body. The Byzantines made some surgical advances, and the Arabs developed the use of drugs in the treatment of disease; yet Galen remained the only real medical authority of Christendom during the whole of this black millenium. The frightful superstition of the times smothered all originality of thought; hence, the infrequent and relatively unimportant discoveries recorded led to no philosophical changes. The greater part of Europe, in fact, was in such a state intellectually that, by the beginning of the thirteenth century, the whole great legacy of learning left by the Greeks was becoming a distorted tradition. To restore classical authority was an objective of humanism; and at least one physician of this period should be acceptable as a colleague to the Humanists of to-day, for Arnald of Villanova dedicated his life to divesting the current leechcraft of its accumulation of worse errors and to reestablishing in pristine purity the teachings of Hippocrates and Galen. But there was a better way than that of Humanism. Reference to authority, whether of Greece or of Arabia, could not lead onward. The course of progress is inquiry, and all through the next three centuries a few doughty souls took this course. They should command our respect, even though they made no outstanding discoveries; for they sought for truth where truth can be found, ofttimes at considerable cost. Peter of Abano, one of the first great lights of Padua, was persecuted for expressing the belief that diseases had natural rather than supernatural causes, and avoided the fagots of the church only by dying opportunely.

Obviously the organic sciences had no structure at the beginning of the sixteenth century. There existed only the Greek foundation, frayed and weather-beaten. The New World, therefore, is no newer than biology. It is no more than justice to say that biology, in the true sense, began when Vesalius the Fleming, just turned twenty-three, was given the chair of surgery and anatomy at the University of Padua in 1537. Vesalius cast aside authority and, trusting solely to his own observations, labored to such purpose that in five years he was able to publish the monumental folio "De Humani Corporis Fabrica," illustrated with the beautiful drawings of that gifted student of Titian, John de Calcar. His work received the vigorous opposition usually accorded to innovators. He had found no incorruptible resurrection bone which theologians had held must exist; he had discovered that man has the same number of ribs on each side of the body, to the great horror of the students of Genesis; and he had caught the ancient master, Galen, in numerous errors. But the efforts of the opposition had little effect. Vesalius, together with his lesser contemporaries, Eustachius and Fallopius, had established anatomy as an observational science; and shortly after, with the aid of the newly discovered microscope, it was carried to great heights by Malpighi in Italy, by Leeuwenhoek, Swammerdam, and Lyonet in Holland, by Reaumur in France, and by Hooke and Grew in England. Probably no greater morphological work has ever been completed than the entomological dissections made by the brilliant Italian and his distinguished co-workers from the Low Countries.

In the meantime biology had set another milestone in its course. William Harvey (1578-1667) had demonstrated the circulation of the blood, and thus had laid a foundation for the quantitative study of physiological processes. Without the aid of the microscope Harvey was unable to trace the capillaries and to interpret their function, this discovery falling to the lot of Malpighi six years before Harvey's death. But Harvey did something better. He used his reasoning power. By observing carefully the action of the heart and the difference in structure of the veins and the arteries, he was able to show definitely that the quantity of blood pumped into the aorta in a given time makes its return to the heart necessary, since in less than half an hour a quantity of blood greater than that contained in the whole body passes into the great artery. The consequences of this discovery were epoch-making, in that it was fundamental to a true idea of respiration and hence to the proper conception of the body chemistry. But it was more than this. It showed that biology could pass beyond the mere classificatory stage and begin to compare relationships between observed phenomena.

During the latter part of the seventeenth century, the whole of the eighteenth century, and the first quarter of the nineteenth century, biology was by no means stationary. An enormous quantity of carefully collated observations were given to the public. Life histories of thousands of organisms were completed. The organic world was enlarged by the discovery of protozoa and bacteria. Botany flourished. Linnaeus put the classification of animals and plants on a sounder and more satisfactory basis. Lamarck endeavored to demonstrate organic evolution. Nevertheless, biology had not learned to walk, or to run, as it does at the present day; it still crept. Its progress was so slow that if one takes the total biological knowledge of to-day - weighted in proportion to its importance - as one hundred, ninety-nine parts of this knowledge have been obtained during the past century, the full span of a single human life. This fact makes the future seem quite rosy.

In 1828 a new field was entered. Wohler made urea in his laboratory. For the first time a product, until that day known only as the waste of animal activity, was produced by artifice. Henceforth all organic activity was inter-pretable in the terms of chemistry. To-day the whole sequence of chemical changes from the intake of raw food to the resultant bone and muscle is pretty well mapped out. The way in which the food breaks down during digestion, the manner in which the blood acts as carrier of the resultant constituents, and the method by which even the synthesis of proteids occurs, can all be traced with a considerable degree of accuracy. And from the knowledge gained through studying normal metabolism, our biochemists have learned much concerning the abnormal. Medicine has profited. Pathologists already utilize chemical tests to discover whether organs are functioning properly; and the day is not far away when much organic deficiency - whether hereditary or the result of disease - can be made good by the compounds of the commercial chemist. Insulin is the herald of these good tidings.