  The second part of the De ente et essentia proposes arguments, mainly based on Aquinas that deny the identity of essence and existence. Dietrich refutes each one of these arguments. The principal argument from Aquinas that Dietrich refutes is based on the premise that it is possible to understand what something is without knowing that it exists. Thus it follows according to Aquinas that esse is not included in the understanding of a thing’s essentia, and therefore must be distinct from it. Dietrich responds to this argument by challenging its premise. An essence is such only because it refers to an existent. That this is so is seen from the very etymology of the word “essence” as accounted for by St.  Augustine who argued that “essentia” is derived from “esse”. But the issue that lies between Dietrich and his confrere is not one of words but of principles. Armand Maurer, in his important article “The De Quidditatibus Entium of Dietrich of Freiberg and its Criticism of Thomistic Metaphysics”, sums the matter up well when he observes: