The brain is a computer, a chemical regulator, and a number of other things. Those are functional descriptions. The eye is an optical sensor, built in part on a

The brain is a computer, a chemical regulator, and a number of other things. Those are functional descriptions. The eye is an optical sensor, built in part on a jelly and protein substrate, just like the rest of our bodies. Put another way, the eye is composed of jelly (among other things), but the brain isn't composed of a computer (among other things). It's a difference between function and composition.