You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete.

I recognize the right and duty of this generation to develop and use our natural resources, but I do not recognize the right to waste them, or to rob by wasteful use, the generations that come after us.

if we do act, in however small a way, we don't have to wait for some grand utopian future. 
The future is an infinite succession of presents, and to live now as we think human beings 
should live, in defiance of all that is bad around us, is itself a marvelous victory.

It is a wretched taste to be gratified with mediocrity when the excellent lies before us.

It is not OK in this culture to talk to friends about causes you believe in, much less to ask them to join in. It's OK to blast perfect strangers with crass messages every hour of the day, but it's a tinge embarrassing, it brings up some shyness, it seems an intrusion, it risks rejection to share real heartfelt commitments. It's easier to share our cynicism with strangers than our dreams with friends.

There is nothing more difficult to carry out, nor more doubtful of success, nor more dangerous to handle, than to initiate a new order of things.  For the reformer has enemies in all those who profit by the old order, and only lukewarm defenders in all those who would profit by the new order, this lukewarmness arising partly from fear of their adversaries, who have the laws in their favour; and partly from the incredulity of mankind, who do not truly believe in anything new until they have had the actual experience of it.

To the dull mind all nature is leaden. To the illumined mind the whole world burns and sparkles with light.

As a single footstep will not make a path on the earth, so a single thought will not make a pathway in the mind. To make a deep physical path, we walk again and again. To make a deep mental path, we must think over and over the kind of thoughts we wish to dominate our lives.

Each second we live is a new and unique moment of the universe, a moment that never was before and never will be again.

At first people refuse to believe that a strange new thing can be done, then they begin to hope it can be done, then they see it can be done - then it is done and all the world wonders why it was not done centuries ago.