On various occations in different novels and novelettes I have seen "were" after singular/third person, but in school I was thaught that after he/she/it, one should always write "was". For example (from a famous novel):
She looked at him silently, as if a voice within her were saying...
Is it correct to put "were" in the sentence above? Would it be wrong to replace "were" with "was"? Is there anything else of value to know of, in this matter?
" if . . . were" expresses the opposite of fact. For example,
EX: If I were rich (but I'm not rich), I would . . . .
EX: . . . as if a voice were saying (but there really isn't a voice saying) . . . .
"was" expresses the indicative. For example,
EX: If I was to take the job (I'm considering taking it), I would . . . .
EX: If I were to take the job (I'm not considering taking it; I'm speaking hypothetically), I would . . . .
Losing the Subjunctive
It isn't actually the subjunctive. People often call the "were" of "I wish I were" subjunctive, but that term is much better used (as in The Cambridge Grammar of the English Language) for the construction with "be" seen in "I demand that it be done." The "were" form is often wrongly called a past subjunctive, but of course "it were done" is not a past tense of "it be done". The difference between the two is that the subjunctive construction occurs with any verb: "I demand that this cease" is a subjunctive (notice "this cease", not "this ceases"). The relic form in "I were" is only available for "be". For all other verbs you use the preterite: "I wish I went to New York more often." The Cambridge Grammar calls the "were" form the irrealis [i.e., plain counterfactual] form. It is surviving robustly in expressions like "if I were you", but even there it has a universally accepted alternate "if I was you", and there is no semantic distinction there to preserve.