Nyanaponika Thera's Heart of Meditation & Śamatha

I chose Nyanaponika Thera’s the Vision of Dhamma as my first book by this teacher and now see it will take several weeks for a first read for even some preliminary digestion. My question is about the book I didn’t choose, the Heart of Buddhist Meditation. Because of How Early Buddhism Differs from Theravada and a Swift Pair of Messengers I have become aware of an interest in how a teacher comes down on the issue of Śamatha. I just want some insight rather than a defense of a position.