Clifford D. Simak quotes - page 8
A machine, a mechanism, no more than a tool - technological brother to the hoe, the wrench, the hammer - and yet as far a cry from these as the human brain was from that first amino acid which had come into being on this planet when the Earth was very young. 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. For each new development produced, as side effects, so many other possibilities, so many other roads to travel, that with each step one took down any given road there were more paths to follow. There'd never be an end, he thought - no end to anything.
Clifford D. Simak