Public life is a situation of power and energy; he trespasses against his duty who sleeps upon his watch, as well as he that goes over to the enemy.
 Edmund Burke, Thoughts on the Cause of the Present Discontents (1770). copy citation

Context

“To be fully persuaded, that all virtue which is impracticable is spurious and rather to run the risque of falling into faults in a course which leads us to act with effect and energy, than to loiter out our days without blame, and without use. Public life is a situation of power and energy; he trespasses against his duty who sleeps upon his watch, as well as he that goes over to the enemy. There is, however, a time for all things. It is not every conjuncture which calls with equalforce upon the activity of honest men; but critical exigences now and then arise; and I am mistaken, if this be not one of them.” source