Agues come on horseback, but go away on foot.

The rider and the walker represent two different speeds: a feverish illness can take hold suddenly, then fade only gradually.

The proverb contrasts the speed of becoming ill with the slower process of recovering. It acknowledges how frustrating that imbalance can feel.

Use it when a feverish illness began abruptly but recovery is proving slow. It expresses patience with the pace of improvement without predicting when someone will feel well again.