Merleau-Ponty (1908-1961) was one of the more recent representatives of a tradition in 20th century philosophy known as “phenomenology.” (Edmund Husserl, 1859-1938, and Martin Heidegger, 1889-1976, who show up repeatedly in the footnotes, were earlier figures in this movement.) Merleau-Ponty will refer to Augustine, and you should think about the relation between their views of time, but it may be even more helpful to think of what he says in connection with McTaggart and James since he can be seen to address the sorts issues raised by each of them.
This selection has no subdivisions, but you might think of it as falling into three parts: a primarily critical discussion at the beginning (pp. 177-182), a middle section (pp. 182-188) leading up to and including a discussion of the diagram on p. 184, and the long concluding paragraph (pp. 188-190).
The Westphal and Levenson anthology contains a selection from the work of Husserl where Merleau-Ponty finds his diagram. Notice, however, that the similar diagram on p. 35 in the anthology is oriented differently. The vertical lines in Merleau-Ponty—which link the successive Abschattungen (literally, ‘shadowings’) of a given event—correspond to the diagonals pointing down and to the right in Husserl. Husserl’s vertical lines represent consciousness of the past at a given time, something that appears in the lines pointing down and to the left in Merleau-Ponty’s diagram. (Think about the term Abschattung—of which Abschattungen is the plural—when you first encounter it on p. 184 because you will run into it repeatedly thereafter.)