Максимальная польза

Yesterday I read  in Pascal Mercier's 'Night train to Lisbon': 'From time to time in the city, he had run into a student he had taught many years earlier. They weren't boys and girls now, but men and women with spouses, professions and children. He was taken aback when he saw changes in their faces. Sometimes just because of change: a premature bitterness, a harried look, a symptom of serious illness. But what usually startled him was the simple fact that the altered faces indicated the incessant passing of time and the merciless decline of all living things. Then he looked at his hands with their first age spots...'
Coming across my former undergraduates I usually feel almost the same except for what startles me is their aging against my being as young as I used to be.