I had been impressed by the fact that biological systems were based on molecular machines and that we were learning to design and build these sorts of things.

It's a lot easier to see, at least in some cases, what the long-term limits of the possible will be, because they depend on natural law. But it's much harder to see just what path we will follow in heading toward those limits.

After realizing that we would eventually be able to build molecular machines that could arrange atoms to form virtually any pattern that we wanted, I saw that an awful lot of consequences followed from that.

K. Eric Drexler Quotes