“I have no doubt that it is part of the destiny of the human race in it's gradual improvement, to leave off eating animals.”
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Henry David Thoreau 385
1817-1862 American poet, essayist, naturalist, and abolitio… 1817–1862Related quotes

“The human race has improved everything but the human race.”
In "Wages are Going Lower!" (1951), William Joseph Baxter wrote, "One might almost say that the human race seems to have improved everything except people." Variations of this quote have appeared since both with and without attribution to Adlai Stevenson, but no documented connection to Stevenson is known.
Misattributed
On the conditions faced by hurlers. The Journal http://thescore.thejournal.ie/lar-corbett-the-conditions-were-being-asked-to-play-in-arent-fit-for-a-horse-786654-Feb2013/

“I almost think it is the ultimate destiny of science to exterminate the human race.”
Gryll Grange, chapter XIX (1860).
“John Norris: Vegetarian Testimonial,” video ad for People for the Ethical Treatment of Animals (26 August 2011) https://www.youtube.com/watch?v=9LnCbT3ayvM.
"Molly Cameron - Cycling" http://www.organicathlete.org/post/vegan-athlete-molly-cameron#.W12sVP4UlgU, interview with Organic Athlete (9 March 2006).

“I want to live, breathe,
I want to be part of the human race”
The Bends
Lyrics, The Bends (1995)

"American Facts" in Life Without and Life Within (1860) edited by Arthur Buckminster Fuller, p. 108.

As quoted in Durrell: The Authorised Biography (1999) http://books.google.com/books?id=iyRFAAAAYAAJ&q="Look+at+it+this+way+Anyone+who+has+got+any+pleasure+at+all+from+living+should+try+to+put+something+back+life+is+like+a+superlative+meal+and+the+world+is+the+maitre+d'hotel+What+I+am+doing+is+the+equivalent+of+leaving+a+reasonable+tip"Gerald by Douglas Botting
Context: A sparrow can be as interesting as a bird of paradise, the behaviour of a mouse as interesting as that of a tiger. Our planet is beautifully intricate, brimming over with enigmas to be solved and riddles to be unravelled.
Many people think that conservation is just about saving fluffy animals – what they don’t realise is that we’re trying to prevent the human race from committing suicide … We have declared war on the biological world, the world that supports us … At the moment the human race is in the position of a man sawing off the tree branch he is sitting on.
Look at it this way. Anyone who has got any pleasure at all from living should try to put something back. Life is like a superlative meal and the world is the maître d'hôtel. What I am doing is the equivalent of leaving a reasonable tip. … I'm glad to be giving something back because I've been so extraordinarily lucky and had such great pleasure from it.