What is the author's style in Collected Fictions by Jorge Luis Borges?

The book is broken up into 9 different collections of stories, published between the years 1935 and 1983, a couple of years before the author's death. There are over 60 short stories of from 3 to 15 pages. In addition there are a group of ultra-short stories and themes, with about 35 or more of this type of work. Some stories are short, because they are written to illustrate a special person or interesting type of social phenomenon. For example, the story "Funes, His Memory" is explicitly written to tell of the incredible memory of the crippled young man, Ireneo Funes, and how he prides himself on his incredible memory. In a longer, a more developed story, "The Immortal," the story begins with a man who has a goal, in this case to become immortal and see the City of the Immortals.