...by John Emms is a book I would recommend for anyone interested in learning positional basics. Be aware that the title Simple Chess is the same as a much earlier work by Michael Stean published in 1978.
Emms covers outposts, the two bishops, and the isolani, etc. and uses over 50 modern grandmaster games. A lot of his explanations are written in prose, not just a list of variations. Emms shows how strategic ideas arise from the openings and how they are applied. What’s really good that in many games Emms shows how these positional elements lead to superior positions that can be resolved tactically.
Players in the 1400-1700 range should find it helpful.