"Whereas for Plato, the essence (ideal object) is actually independent of particular things, for Aristotle essence is real only when it is actualized, that is, only as it realizes itself in phenomenal objects and therein takes on some appearance detectable by sense experience. In this manner, Aristotle solved the age-old metaphysical problem of the antithesis of Heraclitean objects in a state of multiplicity and flux with the Parmenidean motionless one Being. For Aristotle, all nature everywhere is seeking to realize itself, to develop its potentialities into actualities, to realize its possibilities, as the seed of a rose does when it comes into the beauty of full flower...."
Sahakian, History of Philosophy (Barnes & Noble, 1968).