If we take science as our sole guide, if we accept and hold fast that alone which is verifiable, the old theology must go.
A man can get discouraged many times but he is not a failure until he begins to blame somebody else and stops trying.
If you think you can do it, you can.
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.
Science has done more for the development of western civilization in one hundred years than Christianity did in eighteen hundred years.
I go to nature to be soothed and healed, and to have my senses put in order.
A man can fail many times, but he isn't a failure until he begins to blame somebody else.
Leap, and the net will appear.
I seldom go into a natural history museum without feeling as if I were attending a funeral.
The lure of the distant and the difficult is deceptive. The great opportunity is where you are.
The smallest deed is better than the greatest intention.
Joy in the universe, and keen curiosity about it all - that has been my religion.
The secret of happiness is something to do.
To treat your facts with imagination is one thing, to imagine your facts is another.
The Kingdom of Heaven is not a place, but a state of mind.