The whole conception of Plato in this connection is based on the assumption that there is such a thing as knowledge. If all things are ever in change, then knowledge is impossible; but conversely, if there is {165} such a thing as knowledge, then there must be a continuing object of knowledge; and beauty, goodness, [253] reality are then no dreams. The process of apprehension of these 'thoughts of God,' these eternal objects of knowledge, whether occasioned by sensation or not, is essentially a process of self-inquiry, or, as he in one stage called it, of Reminiscence. The process is the same in essence, whether going on in thought or expressed in speech; it is a process of _naming_. Not that names ever resemble realities fully; they are only approximations, limited by the conditions [254] of human error and human convention. There is nevertheless an inter-communion between ideas and things. We must neither go entirely with those who affirm the one (the Eleatics), nor with those who affirm the many (the Heracliteans), but accept both. There is a union in all that exists both of That Which _Is_, and of that concerning which all we can say is that it is _Other_ than what is. This 'Other,' through union with what is, attains to being of a kind; while on the other hand, What Is by union with the 'Other' attains to variety, and thus more fully realises itself. [258] That which Plato here calls 'What Is' he elsewhere calls 'The Limiting or Defining'; the 'Other' he calls 'The Unlimited or Undefined.' Each has a function in the divine process. The thoughts of God attain realisation in the world of things which change and pass, through the infusion {166} of themselves in, or the superimposing of themselves upon, that which is Nothing apart from them,--the mere negation of what is, and yet necessary as the 'Other' or correlative of what is. Thus we get, in fact, _four_ forms of existence: there is the Idea or Limiting (apart); there is the Negative or Unlimited (apart), there is the Union of the two (represented in language by subject and predicate), which as a whole is this frame of things as we know it; and fourthly, there is the _Cause_ of the Union, which is God. And God is cause not only as the beginning of all things, but also as the measure and law of their perfection, and the end towards which they go. He is the Good, and the cause of Good, and the consummation and realisation of Good. This absolute Being, this perfect Good, we cannot see, blinded as we are, like men that have been dwelling in a cave, by excess of light. We must, therefore, look on Him indirectly, as on an image of Him, in our own souls and in the world, in so far as in either we discern, by reason, that which is rational and good. [269]