He who lives without folly isn't so wise as he thinks.
Francois de La Rochefoucauld (1613 - 1680)

'François VI, duc de La Rochefoucauld, le Prince de Marcillac (September 15, 1613 – March 17, 1680), was a noted French author of maxims and memoirs, as well as an example of the accomplished 17th-century nobleman. He was born in Paris in the Rue des Petits Champs, at a time when the royal court oscillated between aiding the nobility and threatening it. Until 1650, he bore the title of Prince de Marcillac.' Wikipedia.

Also by Rochefoucauld:
Many people despise wealth, but few know how to give it away.

Few things are impracticable in themselves; and it is for want of application, rather than of means, that men fail to succeed.