Note the interpretation of the indefinite determiner (on line 2) as a generalized quantifier—in effect a second-order predicate over two ordinary properties, where these properties have intersecting truth domains. We could have used an atomic symbol for this second-order predicate, but the above way of expanding it shows the relation of the generalized quantifier to the ordinary existential quantifier. Though it is a fairly self-evident matter, we will indicate in section 4.1 how the sentence  “Thetis loves a mortal” yields the following representation after some lambda-conversions: