At the beginning of the sixteenth century--the period with which our history now has to deal--the only available knowledge of anatomy was that which had been supplied by Galen in the third century of the Christian era, and which had been handed down through all the intervening centuries as something absolutely correct and not to be challenged. But the time had arrived when men were no longer willing to accept as truth the teachings of any individual until they had subjected them afresh to the most searching investigations; and thus it came about that a group of remarkably able men devoted all their energies, during the greater part of the sixteenth century, to a very critical study of human anatomy. As the work accomplished by these men constitutes a very important chapter--perhaps the most important chapter--in the history of medicine, I may be pardoned if I devote a disproportionately large amount of space to the consideration of the careers of the more prominent of these founders of modern anatomy, and to an enumeration of the details of the work which they accomplished, and which furnished the most complete verification of the truth stated by Francis Bacon, Lord Verulam (1561–1626), in the following words (_translation_):-- Man has no other means of getting at and revealing the truth than by induction coupled with a never-tiring, unprejudiced observation of nature and an imitation of her operations. Actual facts must first be collected, and not created by a process of speculation. One of the earliest and most thorough students of human anatomy was Marc Antonio della Torre (1473–1506), who belonged to an honorable family of Verona, several members of which had attained distinction as physicians. He planned to publish a treatise on anatomy, and, with this object in view, secured the assistance of Leonardo da Vinci (1452–1515), the celebrated painter, architect and civil engineer, to make life-size pictures of the parts which he had dissected with such care. But, after the latter had completed many of the drawings which were intended to serve as illustrations for the projected treatise, Della Torre unexpectedly died, and the book was never finished. Quite a number of the drawings, however, found their way to England, and for many years past they have been carefully treasured at Windsor Castle and in certain private collections. If Della Torre’s life had been spared it is highly probable that his treatise on anatomy, equipped with illustrations copied from this great artist’s drawings, would have constituted a formidable rival of Vesalius’ famous work.