Man is a clever animal who behaves like an imbecile.
Very little of the great cruelty shown by men can really be attributed to cruel instinct. Most of it comes from thoughtlessness or inherited habit. Extract from 'Memories of childhood and youth.'
A man is ethical only when life, as such, is sacred to him, that of plants and animals as that of his fellow men, and when he devotes himself helpfully to all life that is in need of help.
If a man loses his reverence for any part of life, he will lose his reverence for all of life.