What is the author's style in When Nietzsche Wept by Irvin D. Yalom?

The vocabulary of the story is quite medical. Of course, many of the modern medical terms we use today have changed from their 1882 counterparts. Thus, depression is called "melancholia," and mental illness is called "hysteria," which, incidentally comes from the Greek word for "womb," because it was assumed that only women suffered from hysteria.