If you're going through hell, keep going.
Problems are not stop signs, they are guidelines.
I can, therefore I am.
The dog that trots about finds a bone.
The wise does at once what the fool does at last.
It's always too early to quit.
Never complain and never explain.
To be a good loser is to learn how to win.
Only the educated are free.
Either you run the day or the day runs you.
The frontiers of knowledge in the various fields of our subject are expanding at such a rate that, work as hard as one can, one finds oneself further and further away from an understanding of the whole.