Suddenly, a light bursts forth, pure and alone.  We wonder whence it came: from the outside, or from the inside?  Once it disappears, we say, “It was inside—and yet, no, it wasn’t inside.”  We must not try to learn when it comes, for here there is no “whence.”  The light comes from nowhere, and it goes nowhere; it simply either appears or does not appear.  This is why we must not chase after it, but quietly wait for it to appear, preparing ourselves to be spectators, as the eye waits for the rising sun.

Plotinus, Enneads, V