 The natural way to proceed, then, is to begin with inquiry (historia), with the aim of grasping the differences between, and attributes of, all the animals; and then to attempt to discover their causes. This is natural because, given that our goal is demonstrative understanding, we want to end up with a clear distinction between the facts to be explained (the peri hôn) and their explanation (the ex hôn). This statement echoes the summary, in APo. I 10, of the components of demonstrative knowledge: