The I, or 'pure ego,' is a very much more difficult subject of inquiry than the Me. It is that which at any given moment _is_ conscious, whereas the Me is only one of the things which it is conscious _of_. In other words, it is the _Thinker_; and the question immediately comes up, _what_ is the thinker? Is it the passing state of consciousness itself, or is it something deeper and less mutable? The passing state we have seen to be the very embodiment of change (see p. 155 ff.). Yet each of us spontaneously considers that by 'I,' he means something always the same. This has led most philosophers to postulate behind the passing state of consciousness a permanent Substance or Agent whose modification or act it is. This Agent is the thinker; the 'state' is only its instrument or means. 'Soul,' 'transcendental Ego,' 'Spirit,' are so many names for this more permanent sort of Thinker. Not discriminating them just yet, let us proceed to define our idea of the passing state of consciousness more clearly. =The Unity of the Passing Thought.=--Already, in speaking of 'sensations,' from the point of view of Fechner's idea of measuring them, we saw that there was no ground for calling them compounds. But what is true of sensations cognizing simple qualities is also true of thoughts with complex objects composed of many parts. This proposition unfortunately runs counter to a wide-spread prejudice, and will have to be defended at some length. Common-sense, and psychologists of almost every school, have agreed that whenever an object of thought contains many elements, the thought itself must be made up of just as many ideas, one idea for each element, all fused together in appearance, but really separate. "There can be no difficulty in admitting that association _does_ form the ideas of an indefinite number of individuals into one complex idea," says James Mill, "because it is an acknowledged fact. Have we not the idea of an army? And is not that precisely the ideas of an indefinite number of men formed into one idea?" Similar quotations might be multiplied, and the reader's own first impressions probably would rally to their support. Suppose, for example, he thinks that "the pack of cards is on the table." If he begins to reflect, he is as likely as not to say: "Well, isn't that a thought of the pack of cards? Isn't it of the cards as included in the pack? Isn't it of the table? And of the legs of the table as well? Hasn't my thought, then, all these parts--one part for the pack and another for the table? And within the pack-part a part for each card, as within the table-part a part for each leg? And isn't each of these parts an idea? And can thought, then, be anything but an assemblage or pack of ideas, each answering to some element of what it knows?"