Plato further expounds the determinate reality of these sensuous things, or their simple determinateness. In this world of change form is figure in space; for as in the world, which is the immediate image of the eternal, time is the absolute principle, here the absolute ideal principle is pure matter as such, _i.e._ the existence of space. Space is the ideal essence of this phenomenal world, the mean which unites positivity and negativity, but its determinations are figures. And, indeed, of the different dimensions of space, it is surface which must be taken as true reality, for it is the absolute mean between the line and point in space, and in its first real limitation it is three; similarly the triangle is first among the figures, while the circle has no limit as such within it. Here Plato comes to the deduction of configuration, in which the triangle forms the principle; thus triangles form the essence of sensuous things. Hence he says, in Pythagorean fashion, that the compounding and uniting together of these triangles, as their Idea pertaining to the mean, constitutes once more, according to the original number-relations, the sensuous elements. This is the principle, but how Plato determines the figures of the elements, and the union of the triangles, I refrain from considering.[57] From this point Plato passes to a system of Physics and Physiology into which we have no intention of following him. It is to be regarded as a first, childlike endeavour to understand sensuous phenomena in their manifold character, but as yet it is superficial and confused. Sensuous manifestations, such as the parts and limbs of the body, are here taken into consideration, and an account of this is given intermingled with thoughts which resemble our formal explanations, and in which the Notion really vanishes. We have to remember the elevated nature of the Idea, as being the main point of excellence in his explanations, for, as far as the realization of the same is concerned, Plato merely felt and expressed it to be a necessity. Speculative thought is often recognizable, but, for the most part, consideration is directed to quite external modes of explanation, such as that of end. The method of treating Physics is a different one from ours, for while with Plato empirical knowledge is still deficient, in modern Physics, on the other hand, the deficiency is found in the Idea. Plato, although he does not seem to conform to our theory of Physics, ignoring as it does the theory of life, and though he proceeds to talk in a childlike way in external analogies, yet in certain cases gives utterance to very deep perceptions, which would be well worthy of our consideration if the contemplation of nature as living had any place with our physicists. His manner of relating the physiological to the physical would be as interesting. Certain portions of his system contain a general element, such as his representation of colours, and from this he goes on to