Il est aisé d’aller à pied quand on tient son cheval par la bride = It is easy to stoop from state when that state can be resumed at will.
Il n’est si bon cheval qui ne bronche = The best horse may stumble; Accidents will happen.
[Also: Il n’est si bon charretier qui ne verse.]
Il a changé son cheval borgne contre un aveugle = He has changed for the worse; He has made a bad bargain.
Monter sur ses grands chevaux = To ride the high horse.
[A reference to the big war horses used by knights in battle.]
Je lui ai écrit une lettre à cheval = I wrote him a severe letter.
Il est toujours à cheval sur l’étiquette = He is a stickler for etiquette.
Il est bon cheval de trompette = He is not easily dismayed.