One was tempted, Enoch thought, to say that this was as far as a tool could go, that it was the ultimate in the ingenuity possessed by any brain. But that would be a dangerous way of thinking, for perhaps there was no limit, there might, quite likely, be no such condition as the ultimate; there might be no time when any creature or any group of creatures could stop at any certain point and say, this is as far as we can go, there is no use of trying to go farther.