optical illusion

Strauss-Kahn's sudden, astounding, and very definitive-seeming fall might make an optical illusion of his comeback rise.

The burning atmosphere, the motionless air caused doubtless the optical illusion.

But they had, or maybe it was optical illusion on my part, illusion fostered by mental unrest.

When the hand moves back from the brighter light, as it disappears,—is it an optical illusion?

According to Helmholtz, it is senseless to ask whether cinnabar is red as we see it or is only so as an optical illusion.

I stand, as it were, before the raree-show: I see the little puppets move, and I ask whether it is not an optical illusion.