"It probably isn't all that shocking to point out the cones can't be excited and inhibited at the same time. That means that it's impossible to see an object that's simultaneously blue and yellow or red and green. I'm not talking about what happens when you mix those colors and then look at them – obviously, you'd get green and a sort of murky brown if you did that. No, what I'm talking about here are colors that are equal parts blue and yellow at the exact same time. Can you imagine that? Well, you shouldn't be able to, because that's an impossible color."