Brewer's: Keep your Powder Dry
Keep prepared for action; keep your courage up.
Go forth and conquer, Strephon mine, This kiss upon your lips retaining; A precept that is also thine For bids the teardrop hot and straining. Were Mars and Venus, you and I, And both must `keep our powder dry.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894