Update: it has been reported to me tha Geoffrey Mott-Smith is the name of the co-author.
The basic premise of the book is to build on the old saying that "three tempi are worth a Pawn" and extend the idea to say that "two tempi and a doubled Pawn for the opponent" or "three of any of the minor positional advantages on this long list" are worth a Pawn; so, you could simply count up the *points* and evaluate a position.
As a useful Chess Genius(tm), I was full of scorn for this ridiculous oversimplification, but as a Mature Master(tm), I see it as a brilliant generalization that is too imprecise to be of any use in actual play at the Master level, but that is nonetheless a useful tool for thinking about the game, and probably a very useful tool for learning Chess.
Perhaps the only two books you need to turn a talented beginner into a class A player in three months' time are _Point Count Chess_ and Reinfeld's _1000 Sacrifices and Combinations_.
However, in the current context, the importance of the _Point Count Chess_ idea is as a tool for thinking about the game.
The basic premise is that every positional advantage is worth one-third of a Pawn. For example, if you get the Bishop-pair but get a doubled Pawn, it is an even trade; but if you get a doubled isolated Pawn on an open file, you have lost two points.
On reading that last example, any strong player will immediately think of some position in the Sicilian Defense with 1. e4 c5 2. Nf3 e6 3. d4 cd4 4. N:d4 Nf6 5. Nc3 Bb4, after which ...B:c3+ is horrible for Black. This shows some of the practical weakness of the Point Count system, but perhaps it also shows failure to count all of the "points" of the position.
The magical figure of "one-third of a Pawn" seems to be the quantum of advantage in practical play.