If he had smiled why would he have smiled? To reflect that each one who enters imagines himself to be the first to enter whereas he is always the last term of a preceding series even if the first term of a succeeding one, each imagining himself to be first, last, only and alone whereas he is neither first nor last nor only nor alone in a series originating in and repeated to infinity.
The first principle from which stems the moral of about all people at all time; it is summarized in this precept: Love thy neighbour as thyself, and: do as you would be done by.