What does this Macbeth quote mean?

This is after the murder when Macbeth has a guilty conscience. Figuratively, his hands are red with blood. He is using mythology and big words to distance himself from reality. Neptune is the sea god, and ocean water is green (at least in this case). Macbeth asks whether all the ocean (the green one) can wash the blood off his hands, and he answers his own question: No. Incarnadine means to make red. The big words are hard, but read the page out loud slowly and you will see what Shakespeare is doing. All that Latin rolls around the tongue and echoes in the head. You have to say it slowly; there just is no other way. And that brings Macbeth back down to earth with a thump of plain English, and you get that lovely cinematic image of the blood flowing from Macbeth's hands to color the whole ocean red.