If I will (ean qelw). Condition of the third class with ean and the present active subjunctive of qelw. Till I come (ew ercomai). Literally, "while I am coming" (ew and the present indicative, not ew elqw (second aorist active subjunctive). What is that to thee? (ti pro se;). A sharp rebuke to Peter's keen curiosity. Follow thou me (su moi akolouqei). "Do thou me keep on following." That lesson Peter needed.