On Reserve

In all matters keep something in reserve. It is to insure your position ; not all your wit must be spent nor all your energies sapped every time ; even of what you know keep a rear guard, for it is to double your advantage, always to have in reserve something to call upon when danger threatens bad issue ; the support may mean more than the attack, because it exhibits faith and fortitude. An intelligent man always plays safe, wherefore even here that sharp paradox holds : more is the half, than the whole.

Gracian’s Manual, § 170