Quote by Buddha

The thought manifests as the word;
The word manifests as the deed;
The deed develops into habit;
And habit hardens into character;
So watch the thought and its ways with care,
And let it spring from love
Born out of concern for all beings?
As the shadow follows the body,
As we think, so we become.

Please suggest source details if you know: book, page, year, online article address (url), correction (different author...), etc.. Thanks.