Excerpted from wikipedia: William Olaf Stapledon was a British philosopher and author of several influential works of science fiction.
Stapledon's writings directly influenced Arthur C. Clarke, Brian Aldiss, Stanisław Lem, C. S. Lewis and John Maynard Smith and indirectly influenced many others, contributing many ideas to the world of science fiction.
Olaf Stapleton's "Nebula Maker" is a cosmological work about sentient nebulas and their billion year long history as presented to a human observer. The ages which this race undergoes different modes of behavior and politics. It is a stunning view of how such beings relate to the universe itself. Humanity is inconsequential to such physically vast collective intelligence. There are two main nebula characters in the story which are thinly veiled political views of Ghandi and revolutionary spirit of Marxism.
The other four stories deal with Stapleton's philosophy in four specific areas- Christian, scientist, mystic, and revolutionary. These stories are didactic and more of a selfish viewpoint which seems to be for Stapleton's own consumption and are of lesser quality.
Worth reading if you like cosmological fiction that is not Lovecraftian. But the other stories are for philosophy students.