The doctrine of man as the microcosm had its roots far back in antiquity. Medieval writers from the time of Isidore elaborated upon it with detail and ingenuity. In the literature of our period it occurs in many a passing comparison of the phenomena of nature with the human body, such as that of the _De imagine mundi_ where rivers are compared with blood vessels.[637] It forms an important element in the cosmology of Bernard Sylvester’s _De mundi universitate_[638] and of Herrad of Landsperg’s _Hortus deliciarum_.[639] Hildegard of Bingen’s writings are full of similes and medical recommendations based upon it (Fig. 5).[640] In her _Subtilitates_ the abbess says: “In the creation of man from the earth other earth was taken, and all the elements served man because they perceived that he lived; both the elements and man worked together to each others’ advantage in all relationships.”[641] The thought is expressed more clearly in the _Causae et curae_: “Oh, man! Look at man, for man has in himself heaven and earth and all other things that are created, and his form is one and in him all things lie hidden.”[642] To illustrate the detail in which Hildegard worked out this theory we may do no better than to quote from Thorndike’s summary. “She compares the firmament to man’s head, sun, moon, and stars to the eyes, air to hearing, the winds to smelling, dew to taste, and ‘the sides of the world’ to the arms and sense of touch. The earth is like the heart, and other creatures in the world are like the belly. In the _Liber divinorum operum_ she goes into further detail.... From the top of the cerebral cavity to the ‘last extremity of the forehead’ there are seven distinct and equal spaces, by which are signified the seven planets which are equidistant from one another in the firmament. An even more surprising assumption as to astronomical distances is involved in the comparison that as the three intervals between the top of the human head and the end of the throat and the navel and the groin are all equal, so are the spaces intervening between the highest firmament and lowest clouds and the earth’s surface and center.... As the heart is stirred by emotion, whether of joy or of sorrow, humors are excited in the lungs and breast which rise to the brain and are emitted through the eyes in the form of tears. And in like manner, when the moon begins to wax or wane, the firmament is disturbed by winds which raise fogs from the sea and other waters.”[643] The preface to the _Subtilitates_ contains another discussion of the microcosm in the course of which the stones of the earth are likened to bones and it is pointed out that the earth has sweat, humors, and other by-products of the body.[644] Much of the argument of the _Causae et curae_ is based upon the assumption that the very diseases of man have their counterparts in the facts of the macrocosm. _SHAPE, MOVEMENTS, AND SIZE OF THE EARTH_