So all the possible functions are having a party. They're drinking, dancing, chatting each other up, and generally having a great time. Somewhere off in an n-dimensional corner, e^x is sitting all by his lonesome. A group of expenential functions is standing nearby. So 2^x comes up to e^x and says "Come on, man, don't sulk like that, integrate yourself with the rest of us", to which e^x replies "What for, it wakes no difference??"