In the writings of the Crusading age we find a few scattered remarks on the relationship between geographical features and environment and the life of man and animals, or on those branches of our science now called biogeography and anthropogeography. The writings of Bernard Sylvester furnish us with some striking examples. The Platonic and realist conception of the unity of all matter, which was exemplified in the theory of a World Soul and expounded in vivid terms by Theodoric of Chartres, led Bernard in his _De mundi universitate_ to emphasize the close interrelations of all natural phenomena and the influences of the various elements and parts of the universe upon each other. He stressed, for example, the importance of astrological influences, by attributing to the moon control over the tides and other terrestrial phenomena.[1054] In geography he emphasized the influences of terrain on plant and animal life. Thus he says “fruitful land gives birth to wolves, desert to lions, arid land to serpents, woods to bees.”[1055] Elsewhere he explains how the plane tree grows in flat country, the alder in valleys, the box among rocks, the willow on the banks of streams, the fragrant cypress in the mountains, the sacred vine on the slopes, and the olive in well-worked loam.[1056] Neckam also recognized that the growth of plants was governed by the qualities of the earth.[1057] Only about the center of the globe is there really true earth; the surface which we cultivate is not true earth because it is intermingled with particles of air, fire, and other substances. Consequently it follows that in the same territory there may grow herbs by nature both warm and cold and that in certain places oats thrive well and in others barley. There is a very striking passage in Hildegard’s _Subtilitates_ explaining in much detail the influence of various kinds of soil upon agriculture.[1058] Hildegard asserts that there are divers types of soil (_terra_)—black, white, and red. White soil is pallid and sandy and contains much humidity in the form of large raindrops: because of this quality white soil produces great vines and apple orchards but is rather less well adapted for the raising of grains. The latter may better be cultivated upon soil characterized by humidity of finer texture and minuter drops. Black soil contains too much cold and dampness to produce more than a moderate yield; red soil, on the other hand, has the right balance of dampness and dryness and hence produces a quantity of fruits, which, however, through their very abundance fail to attain perfection. And so Hildegard proceeds with a discussion that would have been of a highly utilitarian character, had it only been based more directly upon the observation of the facts of nature. ON MAN