This form of condition corresponds to the use of
Modern English substitutes the present for the more exact future in ordinary future conditions of this class; and often uses shall in the protasis with an emotional force. The English present subjunctive, although somewhat rarely used in the modern language, corresponds more nearly to the Greek subjunctive (“if she be there, he shall not need”: Beaumont and Fletcher).—Since if you do this may be expressed in Greek by ἐὰ_ν ταῦτα ποιῇς or εἰ ταῦτα ποιήσεις ( cross2328), and by εἰ ταῦτα ποιεῖς ( cross2298), the difference in meaning is made clear only by the apodosis. The form ἐὰ_ν ταῦτα ποιῇς in vivid future conditions must be distinguished from the same form in present general conditions (
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].