He who drinks when he is not dry, will be dry when he has no drink.

The proverb warns that satisfying a want before it becomes a need can leave a person without what they require later. Its image of thirst makes the cost of poor timing immediate and concrete.

More broadly, it favors restraint when a supply is limited. Having something available now is not, by itself, a reason to use it up before a greater need arises.

Use it to caution someone against consuming a limited supply too soon. It is especially apt when the person can wait, but may not be able to replace what they use before they need it.