I bring an ostrich to a high and narrow and slippery ridge. I bid him consider the abyss to his left and the abyss to his right.
"You came from nothing to perch here a moment, but soon you will slide to your left and become nothing again. I speak in a parable to convey to you the truth of presentism: the present alone is real. What is not yet is not; what is no longer is not. Now is the time, transient as it is. No nunc stans for you; the nunc movens is all you've got."