Full Idea
The substitution view of quantification explains 'there-is-an-x-such-that x is a man' as true when it has a true substitution instance, as in the case of 'Socrates is a man', so the quantifier can be read as 'it is sometimes true that'.
Gist of Idea
The substitution view of quantification says a sentence is true when there is a substitution instance
Source
Alex Orenstein (W.V. Quine [2002], Ch.5)
Book Reference
Orenstein,Alex: 'W.V. Quine' [Princeton 2002], p.103
A Reaction
The word 'true' crops up twice here. The alternative (existential-referential) view cites objects, so the substitution view is a more linguistic approach.