In Benford's case, beyond anything remotely in harmony with Clarke's far-future saga Against the Fall of Night (later reworked as the better 1956 novel, The City and the Stars). Anyway, for reasons wholly mysterious, here's the 1949 Against the Fall of Night, plus Benford's crashing, effortful modem sequel. In Clarke's original, immortal Alvin--a billion years hence--breaks free of his city Diaspar's self-imposed isolation, and then discovers that all the history his people believed was false. Instead, a great galactic civilization had created an implacably hostile pure mentality, the Mad Mind, and subsequently imprisoned it inside the Black Sun; other, friendly pure mentalities were later created to counter it. In Benford's followup, Alvin's space journeys have allowed the Mad Mind to escape and threaten Earth; an alliance of human, nonhuman, and immaterial creatures, in defeating the Mad Mind, presages the advent of a truly godlike being. Clarke's original was light, pulpish, visionary, and stunning in its ability to convey huge ideas embedded in vast sweeps of time. Benford's intelligent but discordant sequel is heavy, gnarled, and thoroughly predictable, often more like criticism than fiction. So, Clarke's near-best has brought out the usually brilliant Benford's absolute worst--and the upshot is a project ill-conceived, ill-wrought, and irrelevant.