Of the word ΕΙ engraven over the gate of Apollo's temple at Delphi (19)

What then is it that has really a being? That which is eternal, unbegotten, and incorruptible, to which no

time brings a change. For time is a certain movable thing appearing in connection with fleeting matter, always flowing and unstable, like a leaky vessel full of corruption and generation; of which the sayings after and before, it has been and it shall be, are of themselves a confession that it has no being. For to say that what not yet is or what has already ceased to be is in being, how foolish and absurd is it. And as for that on which we chiefly ground the under standing of time,—saying, the instant, present, and now,— this again reason wholly rejects and overthrows; for it is lost between the future and the past, like a flash of light, and is separated into two when we will behold it. Now if the same thing befalls Nature, which is measured by time, as does the time which measures it, there is nothing in it permanent or subsistent, but all things are either breeding or dying, according to their commixture with time. Whence also it is not lawful to say of any thing which is, that it was or shall be; for these are inclinations and departures and changes of that whose nature is not to continue in being.