Nyanaponika introduces Early Buddhist philosophical psychology in detail. He shows that the common and superficial understanding of the Buddhist theory of self - according to which the theory is a mere list of the parts of a self - is wrong and overlooks the Abhidhamma (probably because it is an abstruse section of the Buddhist canon). The theory includes an often overlooked but sophisticated and plausible description of functional relations amongst the parts of a self, and Nyanaponika shows this with astonishing vivacity. This shows that the Early Buddhist theory was an early scientific psychology of a functionalist sort: a monumental acheivement in human intellectual history. All the while, he skilfully shows how the theory is logically connected with the Buddhist notion of psychological self-refinement and nirvana. Still, Nyanaponika and the Abhidhamma ideas he explains seem at times to rely on a dubious empirical method: the introspections of ancient Buddhist masters (which may have included the Buddha himself) who wrote the Abhidhamma texts. As a consequence, some of the descriptions of the parts of the self and their functions seem vague or implausible. Also, although Nyanaponika is good at explaining the philosophical as well as the psychological, one might have liked a bit more discussion of the structure of what appears to be an underlying Buddhist argument that there is no self. The book is of interest to philosophers and psychologists.
A little gem of clarity and succinctness which deals with the deepest concepts of Buddhism.