Letters from a Stoic 85 : 15

What they mean to say is this: "So-and-so is indeed not a man of an angry disposition, but still he sometimes gives way to anger," and "He is not, indeed, inclined to fear, but still he sometimes experiences fear"; in other words, he is free from the fault, but is not free from the passion of fear. If, however, fear is once given an entrance, it will by frequent use pass over into a vice; and anger, once admitted into the mind, will alter the earlier habit of a mind that was formerly free from anger.