I don't think you quite understood it. Let me put it this way,
Consider a capacitor, the voltage across the capacitor is a function of the charge stored. So to increase the voltage one has to add more charge. The least charge that can be added is 1.602*10^-19... This inherent discrete...
I once heard a professor say no electrical signal according to present knowledge is truly analog in amplitude. I find it amazing considering how most schools go with the "world is analog" statement.. any views on this? BTW, the inherent discrete nature of the electric charge is the principle...