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PREFACE
Of the three kingdoms in nature into which the created things are comprehensively classified, man finds his place fixed in the animal kingdom. Though the animal and the vegetable are alike in having, in common, life and growth, the one is not identical with the other but is distinguished from it by possessing the faculty of will potent to perform a complex series of actions for the sake of maintaining its existence and preserving its life from the onslaught of ferocious animals and other individuals of its own class. As for the vegetable naturally no such facilities seem to exist. Pressed by hunger when animals roam about in search of prey, or when a number of them, coming upon something not sufficient for them all to feed upon, engage themselves in a severe conflict over it, or when some of them, too weak and timid to withstand the attack of fierce kinds. flee away for life, one can see what a marvellous and tactful variety of actions denied to plant life they perform.
Since the vegetable kingdom is unlike the animal, in being left unprovided for its defence, it is clear that nature intended her to be used for food by animals; while on the contrary she has forbidden one animal being preyed upon by another by implanting in each a passionate desire for preserving its life and by giving to each the means of accomplishing it. It may even be imagined that, in the remote past, nature could have made even the wild animals subsist solely upon herbs, fruits and roots and that it is only at a later period when certain large sized and ferocious types of animals, belonging to polar regions where they had none of the vegetable products to live upon except animal flesh, migrated into
