What is the author's style in The Memory Palace of Matteo Ricci by Jonathan D. Spence?

The Memory Palace is full of citations and discussions of the best understanding the historical community has of Matteo Ricci's life and times. We see the original painting and ideographs the Matteo Ricci worked with reproduced in the book. Often The Memory Palace take detours into 16th century Chinese or Italian history, important theological debates, the state of 16th and 17th century science, East Asian relations, Greek and Roman philosophy, Confucian theology and so on.