Balzac's "Louis Lambert"

Started reading it because I found it in Flaubert's letters (in this case a letter to Louise Colet):

     At this moment I am as though in the grip of a ghastly terror, and if I am writing you it is perhaps to avoid being alone with myself, the way one lights one's lamp at night when one is afraid. I don't know whether you are going to understand me, but it is very strange. Have you read a book by Balzac called Louis Lambert? I finished it five minutes ago: I am thunderstruck by it. It is the story of a man who goes mad from thinking about intangible things. I cannot shake it off: it has grappled itself on to me in a thousand places. This Lambert is, in all but a few particulars, my poor Alfred.