It's always too early to quit.
To know oneself, one should assert oneself.
The dog that trots about finds a bone.
The wise does at once what the fool does at last.
Things do not happen. Things are made to happen.
Leap, and the net will appear.
Go for it now. The future is promised to no one.
Problems are not stop signs, they are guidelines.
Never complain and never explain.
Either you run the day or the day runs you.
I am a teacher, and I am proud of it. At Cornell University I have taught primarily undergraduates, and indeed almost every year since 1966 have taught first-year general chemistry.