À la fleur de l’âge = In the prime of life.

Il a les nerfs à fleur de peau = His nerves are always on the twitch; He is extremely sensitive.

Fleurette

Conter fleurettes = To say soft nothings.

Flûte

*Ce qui vient de la flûte s’en va au tambour = Lightly come, lightly go; What is dishonestly acquired is easily dissipated.

Foi

C’est un homme sans foi ni loi = He is a man without honour or honesty.

Il est de peu de foi = He is not to be trusted.

Ses ouvrages en font foi = His works prove it.