(no subject)
The use of the symbol ∈ (a stylized form of the Greek epsilon) to denote membership was initiated by the Italian mathematician Giuseppe Peano in 1889. It abbreviates the Greek word ὲστὶ, which means `is.' The underlying rationale is illustrated by the fact that if B is the set of all blue objects, then we write ``x ∈ B'' to assert that x is blue. (Enderton, 1977)
Do you see it there? Our old friend? ὲστὶ? esti?
no subject
I always assumed the epsilon meant "element of".