My copy of Poul Anderson's Brain Wave is a New English Library SF Master Series edition, published in 1977. My copy of Greg Bear's Eon is a Gollancz SF Masterworks edition, published in 2002. These are two attempts to keep before the public what are regarded as "classic" works. The blurb for Brain Wave says, "This now-classic novel..." A real classic is, of course, a work that is always in print, usually in multiple editions. Sf classics include The Time Machine.
It may be thought that an sf paperback read for pleasure must be a light and trivial work. I hope that my synopses and analyses of these novels demonstrate that they are dense and serious works. In Brain Wave, there is a single premise and an extremely long list of ingenious deductions from that premise.