It is the purpose of this paper to show that Axiom A2 in Bourbaki's axiomatic system for set theory can be replaced by the weaker statement that every term x defines a set { x of which x is the only element. All references in the paper are to [1], and the terminology and notation of [1] are used. We place ourselves into a theory with specific signs = and , in which Si through S8 are schemas, and Al, A4 and the statement (1) (yx) Coll, (y = x) are axioms. The theory may contain other specific signs, schemas and axioms. Axiom (1) allows us to define a set {x} =Ev (y=x). Criterion C51 (p. 65) then can be proved. It follows that there is a set 4 such that (Vx)(xE4) is true. Sets {I } and, using A4, $(I({ }) can then be constructed. It follows that 4 Ez$({I J), {I} ({4 }), and 4'-x {I4. Let now R in S8 (p. 64) be the relation (x = u andy-4) or (x= v andy= {y}). The relation