In a few texts, Thomas Aquinas says that the first operation of the intellect pertains to (respicit) “the quiddity of a thing” whereas the second operation pertains to “the to be itself of a thing” (esse). But Aquinas also says that quiddities are to the intellect as color is to the power of sight. Statements such as these seem to have led Jacques Maritain and Étienne Gilson to see esse as the proper object of the intellect’s second operation. Against this (...) conclusion, Fr Régis and Ralph McInerny have argued—using Aquinas’s In I Peryermenias, lecture 5—that since ‘is’ is a verb and ‘is’ signifies existence, but all verbs signify the first operation of the intellect, we must be able to form a concept of existence in the first operation of the intellect. This paper does three things. First, it analyzes the nature of the claim made by Maritain and Gilson. Second, it shows from internal textual evidence that “respicit ipsum esse rei” cannot mean what Maritain and Gilson take it to mean. The second operation of the intellect cannot have a proper object distinct from the object of the first operation, which is quiddities. Finally, this paper provides an alternative interpretation of In I Peryermenias, lecture 5, to the one given by McInerny. In that text, Aquinas does not speak about a particular concept of existence in the first operation of the intellect and signified by the verbs ‘is’ or ‘exists.’ Rather, he uses the word ‘esse’ in indirect speech to include generally any form or act joined to a subject by the copula, ‘is.’ Aquinas’s focus is not on what ‘esse’ or ‘est’ signifies, but on the mode in which it signifies (per modum actualitas) absent additional qualifying terms. The conclusion of this paper is that, although the esse contrasted with essence in Aquinas’s metaphysics corresponds to a concept in the intellect’s first operation, nevertheless, like the notions of blindness and of genus, this esse cannot fall properly within the intellect’s object. (shrink)