Keep Your Powder Dry
Meaning
This phrase is used to say that we should do optimal use of resources and save them until they are absolutely needed.
Origin
In 1856, Edward Hayes wrote it in Ballads of Ireland:
“There is a well-authenticated anecdote of Cromwell. On a certain occasion, when his troops were about crossing a river to attack the enemy, he concluded an address, couched in the usual fanatic terms in use among them, with these words – ‘put your trust in God; but mind to keep your powder dry’.”