We often hear of people breaking down from overwork, but in nine cases out of ten they are really suffering from worry or anxiety.
When an end is lawful and obligatory, the indispensable means to it are also lawful and obligatory. 
If you put out your hands, you are a laborer; if you put out your hands and mind, you are a craftsperson; if you put out your hands, mind, heart and soul, you are an artist.
The world can be changed by man's endeavor, and that this endeavor can lead to something new and better. No man can sever the bonds that unite him to his society simply by averting his eyes.
Only those who have the patience to do simple things perfectly ever acquire the skill to do difficult things easily.
The decline of literature indicates the decline of a nation; the two keep in their downward tendency.
Life can only be understood backwards; but it must be lived forwards.
Histories make men wise; poems witty; the mathematics subtle; natural philosophy deep; moral grave; logic and rhetoric able to contend.
I want to bring out the secrets of nature and apply them for the happiness of man. I don't know of any better service to offer for the short time we are in the world.
If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest.
The important thing in life is to have a great aim and the determination to attain it.
The ideals which have lighted my way, and time after time have given me new courage to face life cheerfully, have been kindness, beauty and truth.