A high voltage at a low current delivers lots of power (think the jet of a firehose) and so does a low voltage at a high current (the Thames through London isn't going very quickly, but it'd be a devil of a job to stop it).

I guess I'm still not getting it. Whether the water is coming from a hole in the side of a dyke along the river, or whether it's coming from a same-sized hole in the side of a fire hydrant, the amount of flow is still determined by the pressure behind that hole. How can there be two different kinds of pressure? There's either X pressure behind that hole or there isn't. I don't see how the water can represent both volts and amps.

Unless you're trying to tell me that the amperage is simply a measurement of the flow... and not related to the water pressure at all. Like... say, a paddle wheel with an RPM counter inserted into the stream coming out of the side of the dyke. And the amperage is merely the number on that RPM counter.

Is that what you're saying?

If so, then my whole problem was not realizing that amperage was just a flow measurement. In other words, amperage is determined by the resistance in much the same way that your speed is determined by how hard you press on the gas pedal.

I was thinking amperage was some ethereal secondary property of the electricity itself, somehow altering how "powerful" the voltage was. I thought that the amount of amperage was something that existed behind that dyke. If it's just a scale of measurement representing the amount of water after it's gone through the hole, and not a property of the electricity itself before it's gone through the hole, then I think I finally get it. And the concept is pretty simple.