A beautiful speech in favor of ecological responsibility and respect of native Americans' land rights has been attributed to him. It includes the quote: “Man does not weave this web of life. He is merely a strand of it. Whatever he does to the web, he does to himself.” These however are not his words but a speech written in 1972 by a screenwriter for a documentary about the environment.
Chief Seattle's speech has a much darker, more haunting message about the God of the white man and the end of the Red Man walking on the earth.
"Our dead never forget this beautiful world that gave them being. They still love its verdant valleys, its murmuring rivers, its magnificent mountains, sequestered vales and verdant lined lakes and bays, and ever yearn in tender fond affection over the lonely hearted living, and often return from the happy hunting ground to visit, guide, console, and comfort them."
Read his full speech here