If men knew how to blush at their own actions, how many crimes, and not only those that are hidden, but those that are public and well known, would never be committed!

[Si l’homme savait rougir de soi, quels crimes, non seulement cachés, mais publics et connus, ne s’épargnerait-il pas!]

Jean de La Bruyère (1645-1696) French essayist, moralist

The Characters [Les Caractères], ch. 11 “Of Mankind [De l’Homme],” § 151 (11.151) (1688) [tr. Van Laun (1885)]
    (Source)

(Source (French)). Alternate translations:

If men could blush at their own actions, how many sins, publick and private, would they save by it?
[Bullord ed. (1696)]

If Men knew how to blush at their own Actions, how many Crimes, publick and private, would they save by it!
[Curll ed. (1713)]

If Men could blush for themselves, how many Sins, public and private, would they save by it!
[Browne ed. (1752)]

If a man knew how to blush at his own actions, what crimes, not only secret but public and overt, would he not spare himself!
[tr. Stewart (1970)]