Four characters of 2001 have one great need, to achieve a memory.

Moon-Watcher, the man-ape of the first chapters, cannot remember his father.

He lives only in the present, from which he is redeemed by the monolith's teaching him the future he might have. Contemporary humanity, which Dr. Floyd represents, has a broader time-sense, but must be shocked out of those limits by the discovery of the monolith three-million years old. And Bowman goes to Saturn to join a racemind now considerably older than that.

Dr. Floyd, however, recognizes only his own limit. Moon-Watcher and Bowman not only confront their limit but are forced to return to school as little children in order to overcome it.

The most interesting character struggling with memory is the computer, Hal. He actively suffers, concealing from the crew what has been discovered in the past and what shall happen in the future. Bowman's...