How Do CPU’s Read Data/Instructions?

Assembly language, as I’ve heard, is the language of microprocessors. You write it, it gets “assembled” into binary and the CPU reads it. How does this work? CPU’s are simply made of silicon and some conductive metal, aren’t they? How does the CPU know what a 1 or a 0 is? Perhaps it’s because 0 is off and 1 is on, and impulses flow that way…but how does the computer know how to turn this off and on by “reading” binary? There has to be some sort of magic going on.