their universality. Ideas are necessary, because no thinking can take place without them. They are universal, inasmuch as they are completely divested of the particularity which characterises all the phenomena of mere sensation. To grasp the nature of this universality is not easy. Perhaps the best means by which this end may be compassed is by contrasting it with the particular. It is not difficult to understand that a sensation, a phenomenon of sense, is never more than the particular phenomenon which it is. As such, that is, in its strict particularity, it is absolutely unthinkable. In the very act of being thought something more than it emerges, and this something more cannot be again the particular, for in that case something more would again emerge, and so on for ever. For example, suppose that in thinking a particular object, the additional something which I thought of were one other particular object or ten other particular objects; in that case I maintain that no thinking would have taken place, for I would still be confined to the particular; ten particulars, per se, cannot be thought of any more than one particular can be thought of. When ten particulars, or ten hundred particulars, are thought of, there always emerges in thought an additional something, which is the possibility of other particulars to an indefinite extent. In the operation of thinking, any given number of particulars are always reduced to so many instances, and the indefinite outstanding something which they are instances of is a universal.
