It's always too early to quit.
Only the educated are free.
What you do today can improve all your tomorrows.
Well done is better than well said.
Quality is not an act, it is a habit.
Be gentle to all and stern with yourself.
Never complain and never explain.
The secret of getting ahead is getting started.
I can, therefore I am.
Always desire to learn something useful.
Soon I knew the craft of experimental physics was beyond me - it was the sublime quality of patience - patience in accumulating data, patience with recalcitrant equipment - which I sadly lacked.