Letters 42.4

These men simply lack the means whereby they may unfold their wickedness. Similarly, one can handle even a poisonous snake while it is stiff with cold; the poison is not lacking; it is merely numbed into inaction. In the case of many men, their cruelty, ambition, and indulgence only lack the favour of Fortune to make them dare crimes that would match the worst. That their wishes are the same you will in a moment discover, in this way: give them the power equal to their wishes.

Seneca, Letters to Lucilius 42.4, translated by Richard Mott Gummere