It's from Emerson's lecture on Perpetual Forces
http://www.rwe.org/comm/index.php?optio ... Itemid=232
What we do and suffer is in moments, but the cause of right for which we labor never dies, works in long periods, can afford many cheeks, gains by our defeats, and will know how to compensate our extremest sacrifice. Wrath and petulance may have their short success, but they quickly reach their brief date and decompose, whilst the massive might of ideas is irresistible at last. Whence does the knowledge come? Where is the source of power? The soul of God is poured into the world through the thoughts of men.
The world stands on ideas, and not on iron or cotton ; and the iron of iron, the fire of. fire, the ether and source of all the elements is moral force. As cloud on cloud, as snow on snow, as the bird on the air, and the planet on space in its flight, so do nations of men and their institutions rest on thoughts.