It is a commonplace that eternity is not an endless prolongation of time, has nothing to do with time. Eternity is a characteristic of the mystical experience. The word eternity doubtless meant originally endlessness of time, which must count, therefore, as its literal meaning. But in its religious and metaphysical use it is a metaphor for the characteristic of the experience. For in that experience time drops away and is no more seen.

Time and Eternity - An Essay on the Philosophy of Religion (1952), p. 76