The Passive Sign Convention from Wiki: "In electrical engineering, the passive sign convention (PSC) is a sign convention or arbitrary standard rule adopted universally by the electrical engineering community for defining the sign of electric power in an electric circuit. The convention defines electric power flowing out of the circuit intoan electrical component as positive, and power flowing into the circuit out of a component as negative" All well and good. What I don't understand is what voltages and currents have to do with it. The page goes on to say: "To comply with the convention, the direction of the voltage and current variables used to calculate power and resistance in the component must have a certain relationship: the current variable must be defined so positive current enters the positive voltage terminal of the device." I understand the sign of power can be arbitrarily defined depending on what system you're interested in; however, how can currents and voltages be arbitrarily defined? In a conductor, the actual current will always "flow" in the direction of the Electric Field, from a greater voltage potential. You can't just define the directions of the voltages and currents arbitrarily, unless you also want to rewrite Maxwell's Equations. What am I missing here?