It's always too early to quit.
To know oneself, one should assert oneself.
Begin to be now what you will be hereafter.
Always desire to learn something useful.
By failing to prepare, you are preparing to fail.
Be kind whenever possible. It is always possible.
What you do today can improve all your tomorrows.
You never know what motivates you.
Either you run the day or the day runs you.
Leap, and the net will appear.
As for everything else, so for a mathematical theory: beauty can be perceived but not explained.