Dear Sir,
Greek grammarians nowadays do not teach that ‘… the Greek aorist tense is a “once for all past event” ’ (Brian H. Edwards’ review of Terry L. Johnson’s Commentary on 1, 2 and 3 John, en January 2017).
Rather, the aorist simply portrays the event concerned as a whole; it views the action ‘from a vantage-point outside the action … without reference to its internal structure’ (Buist M. Fanning 1990). So ‘he came’ (Luke 15.20) simply presents the younger son’s journey back to his father as a whole, without focussing on the end of the journey. This allows the next sentence of the parable to state, ‘But while he was still far off – i.e., before he had finished his journey. In certain contexts (e.g. reported speeches), sentences in the aorist don’t even have to refer to past events (e.g. ‘with you I am well pleased’– Mark 1.11).