Well, it's the change in your vertical axis, which is going to be f of x plus h minus f of x over the change in your horizontal axis. And that's x plus h minus x, and we see here the difference is just h over h. And we're going to take the limit of that as h approaches 0. So in the case when f of x is the natural log of x, this will reduce to the limit as h approaches 0, f of x plus h is the natural log of x plus h minus the natural log of x, all of that over h. So this right over here, for our particular f of x, this is equal to f prime of x. So if we wanted to evaluate this, when x is equal to e, then everywhere we see an x, we just have to replace it with an e. This is essentially expressing our derivative as a function of x. It's kind of a crazy-looking function of x. You have a limit here and all of that, but every place you see an x, like any function definition, you can replace it now with an e. So we can, let me just do that. Whoops, I lost my screen.