Quote by Lao-tzu

When the highest type of men hear Tao,
They diligently practice it.
When the average type of men hear Tao,
They half believe in it.
When the lowest type of men hear Tao,
They laugh heartily at it.
Without the laugh, there is no Tao.

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