Science has done more for the development of western civilization in one hundred years than Christianity did in eighteen hundred years.

• The secret of happiness is something to do.
• Nature teaches more than she preaches. There are no sermons in stones. It is easier to get a spark out of a stone than a moral.
• I still find each day too short for all the thoughts I want to think, all the walks I want to take, all the books I want to read, and all the friends I want to see.
• It is always easier to believe than to deny. Our minds are naturally affirmative.
• The tendinous part of the mind, so to speak, is more developed in winter the fleshy, in summer. I should say winter had given the bone and sinew to literature, summer the tissues and the blood.
• The very idea of a bird is a symbol and a suggestion to the poet. A bird seems to be at the top of the scale, so vehement and intense his life. . . . The beautiful vagabonds, endowed with every grace, masters of all climes, and knowing no bounds -- how many human aspirations are realised in their free, holiday-lives -- and how many suggestions to the poet in their flight and song
• The lure of the distant and the difficult is deceptive. The great opportunity is where you are.
• Science has done more for the development of western civilization in one hundred years than Christianity did in eighteen hundred years.
• Life is a struggle, but not a warfare.
• The spirit of man can endure only so much and when it is broken only a miracle can mend it.