In the history of thought, the discovery of a new concept often represents a major step for the advancement of knowledge.
Blessed Duns Scotus (1266-1308,) for example, introduced into theology the concept of “redemption by preservation,” according to which the Blessed Virgin Mary was redeemed in an even more wonderful way: not by being freed from sin, but by being preserved from sin. 
Similarly, Saint Thomas Aquinas discovered the notion of actus essendi in his Christianizing of Aristotle. In the Wikipedia article Actus Essendi, one reads that “In fact, the contribution of Aquinas to the philosophy of being is precisely this, that he discovered that all Aristotelian acts were in reality ‘potency’ with respect to the actus essendi.”
The discovery of the notion of actus essendi equipped Aquinas with the metaphysical principle he needed to formulate an original and incisive argument for the existence of God. The Actus Essendi Way developed by Aquinas sets him apart from all other philosophers, including Aristotle. 
↑ John Paul II, General Audience, 5 June 1996.
↑ See my article Does God Exist?