A famous quotation on the nature of evil

If only there were evil people somewhere insidiously committing evil deeds, and it were necessary only to separate them from the rest of us and destroy them. But the line dividing good and evil cuts through the heart of every human being. And who is willing to destroy a piece of his own heart?
During the life of any heart this line keeps changing place; sometimes it is squeezed one way by exuberant evil and sometimes it shifts to allow enough space for good to flourish. One and the same human being is, at various ages, under various circumstances, a totally different human being. At times he is close to being a devil, at times to sainthood. But his name doesn't change, and to that name we ascribe the whole lot, good and evil.
Socrates taught us: "Know thyself."
Confronted by the pit into which we are about to toss those who have done us harm, we halt, stricken dumb: it is after all only because of the way things worked out that they were the executioners and we weren't…
From good to evil is one quaver, says the proverb.
And correspondingly, from evil to good.

— Aleksandr Solzhenitsyn