Definition of Ideal
What makes the difference between “ideal” and an ordinary object of desire is that the former is impersonal; it is something having (at least ostensibly) no special reference to the ego of the man who feels the desire, and therefore capable, theoretically, of being desired by everybody. Thus we might define an “ideal” as something desired, not egocentric, and such that the person desiring it wishes that every one else also desired it.
I may wish that everybody had enough to eat, that everybody felt kindly towards everybody, and so on, and if I wish anything of this kind I shall also wish others to wish it. In this way, I can build up what looks like an impersonal ethic, although in fact it rests upon the personal basis of my own desires–for the desire remains mine even when what is desired has no reference to myself. For example, one man may wish that everybody understood science, and another that everybody appreciated art; it is a personal difference between the two men that produces this difference in their desires. (p.115,116)
Russell, B. (1945). A History of Western Philosophy. Simon & Schuster