For the Son of man is come to save that which was lost.
For the Son of man is come to save that which was (or 'is') - lost. A golden saying, once and again repeated in different forms. Here the connection seems to be, 'Since the whole object and errand of the Son of Man into the world is to save the lost, take heed lest, by causing 'offences, ye lose the saved.' That this is the idea intended we may gather from Matthew 18:14.