De La Rochefoucauld
There are a number of good quotes by Francois de la Rochefoucauld on The Quotations Page. Here are three that I like; I could easily add to the list.
No persons are more frequently wrong, than those who will not admit they are wrong.
The height of cleverness is to be able to conceal it.
To establish oneself in the world, one has to do all one can to appear established.
If you stop by, you might find that you recognize some of these.