I am persuaded that no one ever achieves anything worth-while in this world unless he has so great a respect for his work that he compels all other men to respect it. Unless, in a word, he commands his time. Read the life of a great scientist like Agassiz. Was he forever at the world’s beck and call? Not for a single day. To letters inviting him to write, or to lecture for money, he replied that he had no time for those things. He was the custodian of a certain number of days — a number far too small for the great task he had laid out for himself — and he would not be diverted even for an instant.