“It's doubt that drives a man onward.”

“The world owes all its onward impulses to men ill at ease. The happy man inevitably confines himself within ancient limits.”

“Hitherto man had to live with the idea of death as an individual; from now onward mankind will have to live with the idea of its death as a species.”

“All, all, becomes profitable. Education is of the most satisfying and available nature. I am at Smith! Which two years ago was a doubtful dream - and that fortuitous change of dream to reality has led me to desire more, and to lash myself onward - onward.”

“When wise man quits learning, he will be more senile onwards.”

“But the new generation had tasted the wine of philosophy; and from this time onward the rich youth of Rome went eagerly to Athens and Rhodes to exchange their oldest faith for the newest doubts.”