Nothing makes one old so quickly as the ever-present thought that one is growing older.
You can make a good living from soothsaying but not from truthsaying.
Erudition can produce foliage without bearing fruit.
Perhaps pure reason without heart would never have thought of God.
So-called professional mathematicians have, in their reliance on the relative incapacity of the rest of mankind, acquired for themselves a reputation for profundity very similar to the reputation for sanctity possessed by theologians.
He who is in love with himself has at least this advantage - he won't encounter many rivals.