Quoted from EvanDickson:I was trying to figure out what work is supposed to be done if there is no ground for the current applied to the gate pin
One thing to keep in mind. If a voltage is applied it has to be referenced to some point. If the low side isn't specified then it's implied to be ground (or the lowest potential in the circuit).
Think of a battery. If you only connect the (+) terminal and leave the (-) terminal floating, the battery won't do anything.
In the case of an n-channel MOSFET, the connection on the source acts as the low (-) potential and would provide the current ('ground') path you're looking for. Even though the MOSFET gate doesn't require any current to operate, it still needs the voltage (potential, charge) difference between the gate and the source to turn on.
In electronics, I think it's helpful to understand that the components don't know what "ground" means, their operation is only based on the potential differences between their connections.
Don't know if this makes things clearer or more confusing.