MACDUFF I am not treacherous.
MALCOLM But Macbeth is.
A good and virtuous nature may recoil
In an imperial charge. But I shall crave your pardon:
That which you are, my thoughts cannot transpose.
Angels are bright still, though the brightest fell.
Though all things foul would wear the brows of grace,
Yet grace must still look so. (4.3.18-25)
Macduff’s perhaps hurt, or insulted: I am not treacherous, he says, I’m a man of my word, telling the truth—and I too am now Macbeth’s enemy, I too am the opposition. Macbeth’s a traitor though, Malcolm points out: he betrayed his king, broke all the oaths and bonds of loyalty and service. He’s utterly corrupt, and also completely without scruples, ruling by fear, ruthlessly, unpredictably. Even a good and virtuous nature—such as you profess to have, Macduff—may recoil in an imperial charge. You too could be corrupted by him, by the power that he offers, or you could simply obey the king’s orders, the imperial charge, in order to save your skin. Self-preservation can lead even the most noble to compromise, to underhand actions and betrayals. You could, still, be here to betray me, you could be acting as Macbeth’s instrument, his agent.
Malcolm’s demonstrated that he’s not naïve, that he trusts no one on first meeting. But he seems to be deciding that Macduff’s alright, and craves his pardon, asks for forgiveness for doubting him. That which you are, my thoughts cannot transpose: whatever I think of you, or say of you, can’t alter your true nature. And angels are bright still, though the brightest fell, Lucifer, the over-reacher, cast out of heaven for his ambition (like Macbeth): that Lucifer fell doesn’t mean that there are no more angels, and his sin cannot diminish the enduring brightness of the other angels in heaven. Just because other men are bad—just because Macbeth is bad, because he fell, the great hero, trusted and beloved, turned murderer, usurper, tyrant—that doesn’t mean that all men are bad. After all, though all things foul would wear the brows of grace, yet grace must still look so. Even though terrible things, terrible men, disguise themselves with the appearance of virtue, virtue can still look like itself. Foul may be fair, but that need no longer necessitate that fair is foul. There are still good people in the world, and they can still seem as good as they actually are.
