So V Naught, the rate at which the substrate is transformed in the active side, is equal to the product of the rate constant K two of this reaction multiplied by the concentration of this molecule, the complex, this intermediate molecule, by the way, these are reactants, these are products. And this is an intermediate molecule that exists between the reactants and the product. Now, the problem with this equation is, remember, we ultimately want to basically derive a mathematical equation that describes this curve. And so what that means is, whatever this equation is, we have to be able to describe V Naught in terms of the concentration as of the substrate. And this equation has es. And what that means is we can actually use this equation and we have to somehow replace the Es concentration with the S. And that's exactly what we're going to do in all these steps, as we'll see in just a moment.