"the world of appearances is transitory"

Greek Philosopher, Heraclitus, is famous for his doctrine of flux and fire -

Everything flows and nothing abides; everything gives way and nothing stays fixed.

You cannot step twice into the same river, for other waters and yet others, go flowing on.

Time is a child, moving counters in a game; the royal power is a child's.”

Transience or memory in passing attests to the fact that only the present moment is reality. The past is illusionary, and the future is non-existent. In such a circumstance, all appearances, all aspects of the material world are transitory, and only the present moment is real.