“Let no one delay the study of philosophy while young nor weary of it when old.”

“Philosophy when superficially studied, excites doubt, when thoroughly explored, it dispels it.”

“They shall grow not old, as we that are left grow old: Age shall not weary them, nor the years condemn. At the going down of the sun and in the morning, We will remember them.”

“In practice people who study philosophy too long become very odd birds, not to say thoroughly vicious; while even those who are the best of them are reduced by...[philosophy] to complete uselessness as members of society.”

“I saw that they wanted to kill the past. When we are old, we let it die; when we are young and strong, we kill it.”

“That's the duty of the old,' said the Librarian, 'to be anxious on the behalf of the young. And the duty of the young is to scorn the anxiety of the old.'They sat for a while longer, and then parted, for it was late, and they were old and anxious.”