In Galen’s opinion the study of anatomy was important for the philosopher as well as for the physician. An understanding of the use of the parts of the body is helpful to the doctor, he says, but much more so to “the philosopher of medicine who strives to obtain knowledge of all nature.”[654] In the _De usu partium_[655] he came to the conclusion that in the structure of any animal we have the mark of a wise workman or demiurge, and of a celestial mind; and that “the investigation of the use of the parts of the body lays the foundation of a truly scientific theology which is much greater and more precious than all medicine,” and which reveals the divinity more clearly than even the Eleusinian mysteries or Samothracian orgies. Thus Galen adopts the argument from design for the existence of God. The modern doctrine of evolution is of course subversive of his premise that the parts of the body are so well constructed for and marvelously adapted to their functions that nothing better is possible, and consequently of his conclusion that this necessitates a divine maker and planner. In the treatise _De foetuum formatione_ Galen displays a similar inclination but more tentatively and timidly. He thinks that the human body attests the wisdom and power of its maker,[656] whom he wishes the philosophers would reveal to him more clearly and tell him “whether he is some wise and powerful god.”[657] The process of the formation of the child in the womb, the complex human muscular system, the human tongue alone, seem to him so wonderful that he will not subscribe to the Epicurean denial of any all-ruling providence.[658] He thinks that nature alone cannot show such wisdom. He has, however, sought vainly from philosopher after philosopher for a satisfactory demonstration of the existence of God, and is by no means certain himself.[659] [Sidenote: Queries concerning the soul.] Galen is also at a loss concerning the existence and substance of the soul. He points out that puppies try to bite before their teeth come and that calves try to hook before their horns grow, as if the soul knew the use of these parts beforehand. It might be argued that the soul itself causes the parts to grow,[660] but Galen questions this, nor is he ready to accept the Platonic world-soul theory of a divine force permeating all nature.[661] It offends his instinctive piety and sense of fitness to think of the world-soul in such things as reptiles, vermin, and putrefying corpses. On the other hand, he disagrees with those who deny any innate knowledge or standards to the soul and attribute everything to sense perception and certain imaginations and memories based thereon. Some even deny the existence of the reasoning faculty, he says, and affirm that we are led by the affections of the senses like cattle. For these men courage, prudence, temperance, continence are mere names.[662] [Sidenote: No supernatural force in medicine.]