Some of the illustrations commonly given of Plato's Ideal theory may also be instructively used for showing the manner in which his facts are dealt with by the methods of modern science. Thus Plato would say that there is contained in every acorn the ideal type of an oak, in accordance with which as soon as suitable circumstances occur, the acorn will develop itself into an oak, and into no other tree. In the act of development of such a seed into its final growth there are, therefore, two things demanding attention, the intrinsic character of the seed and the external forces acting upon it. The Platonic doctrine draws such a distinction emphatically; its essential purpose is to assert the absolute existence and independence of that innate type and its imperishability. Though it requires the agency of external circumstances for its complete realization, its being is altogether irrespective of them. There are, therefore, in such a case, two elements concerned--an internal and an external. A like duality is perceived in many other physiological instances, as in the relationship of mind and matter, thought and sensation. It is the aim of the Platonic philosophy to magnify the internal at the expense of the external in the case of man, thereby asserting the absolute supremacy of intellect; this being the particular in which man is distinguished from the brutes and lower organisms, in whom the external relatively predominates. The development of any such organism, be it plant or animal, is therefore nothing but a manifestation of the Divine idea of Platonism. Many instances of natural history offer striking illustrations, as when that which might have been a branch is developed into a flower, the parts thereof showing a disposition to arrange themselves by fives or by threes. The persistency with which this occurs in organisms of the same species, is, in the Platonic interpretation, a proof that, though individuals may perish, the idea is immortal. How else, in this manner, could the like extricate itself from the unlike; the one deliver itself from, and make itself manifest among the many?