It is a book that can be read at multiple levels. According to Wikipedia, it has been an inspiration to architects seeking ways of seeing places in their essences. In my reading, focused on my writing, what Calvino writes about a city could well be a way of seeing a book, or seeing life, or looking at life generally. The first city described by Marco to KK is 'Diomira'. The description is three sentences long. This is the third sentence:
"But the special quality of this city for the man who arrives here on a September evening, when the days are growing shorter, and the multicoloured lamps are lighted all at once at the doors of the food stalls and from a terrace a woman cries ooh!, is that he feels envy toward those who now believe they have once before lived an evening identical to this and who think they were happy, that time."
Italo Calvino, Invisible Cities, 1972, translated by William Weaver 1974, Harvest Edition, p 7
Replace the word 'city' with the word 'book'. Yearn to write it. At the same time, see why Calvino had no more to say, needed to say no more, before passing on to describe the second city.
Or consider this as a metaphorical way of describing a novel structure:
"This is the foundation of the city [of Octavia]: a net which serves as passage and support. All the rest, instead of rising up, is hung below: rope ladders, hammocks, houses made like sacks, clothes hangers, terraces like gondolas, skins of water, gas jets, spits, baskets of strings, dumb-waiters, showers, trapezes and rings for children's games, cable cars, chandeliers, pots with trailing plants."ibid, p 7----------*I am going to provide links like that to Better World Books, no income for me, a better deal for you - rather than attach myself to other bookselling sites on the web which encourage a little pyramid selling)