But before we can arrive at them a certain process of initiation is necessary. Let us consider for a moment what these ultimate realities, or, as Plato called them, ideas, are. They are that which veritably Is, as opposed to that which Seems. They are that which is eternal and immutable, as opposed to that which comes into being, grows, passes, and vanishes. They are that which is One as opposed to that which is Many. They are the object of true knowledge, for true knowledge can concern itself only with what is fixed and stable; phenomena are the object of opinion only, conveyed through sensuous perception. They are related to phenomena as substance to shadow. Nothing that our sense makes us aware of in the material world has any real existence, save in so far as it partakes of the nature of an Idea. The Idea is the only reality, and the use of sensible objects is to awaken the mind to perceive the Idea. Paradoxical as it may seem, this insistance upon the empty and unreal character of the sensible world is intended to give true worth and meaning to that world, and is indeed the only way in which this can be done. The sensible universe must die to live. Only by realising its absolute unreality, as an object, can we come to understand its true value as the symbol and image of an object.