If you are alone, you belong entirely to yourself. If you are accompanied by even one companion, you belong only half to yourself or even less in proportion to the thoughtlessness of his conduct, and if you have more than one companion, you will fall more deeply into the same plight.

Just as a good day's work leads to pleasant sleep, so a life well-spent leads to a pleasant death.

Whoever despises the high wisdom of mathematics nourishes himself on delusion.

Theory without practice cannot survive and dies as quickly as it lives. He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may be cast.

I have been impressed with the urgency of doing. Knowing is not enough we must apply. Being willing is not enough; we must do.

Fix your course on a star and then you'll navigate any storm.

You can have no dominion greater or less than that over yourself

Never let your sense of morals prevent you from doing what's right.

As a well-spent day brings happy sleep, so a life well used brings happy death.

Iron rusts from disuse even so does inaction sap the vigor of the mind.