Very few even of the most savage tribes are content to take the world just as it is without speculating as to how it came to be. For time has three dimensions-past, present, and future-and we can no more restrict our thoughts within one of them than we can exist corporeally in Flatland. We are, indeed, told that the Abipones and Esquimaux refuse to trouble themselves with questions of origin, on the ground that the hard facts of life leave no room for otiose discussions; but even they feel obliged to justify their incuriosity. In easier circumstances they, too, would claim the entirely human privilege of 'looking before and after,' as their forgotten progenitors may have done. It is, indeed, difficult to think at all about the framework of nature without attempting to divine, were it only by a crude surmise, the process of its construction. We are instinctively convinced that there is no such thing as fixity of condition. So far, Heracleitus was in the right.