A little leaven leavens a great mass.
More French Proverbs:
He that reckons without his host must reckon again.French
A little help does a great deal.
French
Who loves well is slow to forget.
French
Everything may be bought except day and night.
French
Quarrels do not last long if the wrong is only on one side.
French
The benefice must be taken with its liabilities.
French