At the time Einstein wrote those words, the concepts of microscopic singularity, black holes and big bangs were already implicit in his formulae, For many years, because these concepts were so counterintuitive, and observational evidence lacking, the concept of "space" as being our perception of varying energy densities in an attenuated singular matrix was (so far as I know) absent.

Microscopic singularity "gathers" near energy concentrations (planets, stars) and causes the effect we call "gravity".

Three cheers for Einstein! Again his instinct for the timeless, motionless (and aetherless, in the classical sense)nature of space was right on the money. There is no motion or time possible within the singular condition at either the macroscopic or submicroscopic antipodes of the universe!

Best Wishes, Sam Cox