Reading letters of long-dead thinkers is always a fascinating journey. The literary prowess employed in private conversations may uncomfortably remind many that the last text conversation with their significant other contained 13 emoticons and 3 insincere cases of “lol.” On the other hand, you’d probably quickly tire of unsolicited existential musings via text message.

Not surprisingly, Franz Kafka was no stranger to such screeds in his personal letters. Collected in “Letters to Friends, Family and Editors,” Kafka’s letters range from profound to just plain weird.

In the excerpt of a letter below from 1904, Kafka tells his childhood friend and classmate Oskar Pollack about an 1,800 page book he had just finished, the diaries of German poet Christian Friedrich Hebbel. In dramatic form, Kafka recounts that he could not “take a pen in hand” while reading the book because the vast achievements of Hebbel unsettled his conscience.  What proceeds are Kafka’s thoughts on what makes a good book.

I think we ought to read only the kind of books that wound and stab us. If the book we’re reading doesn’t wake us up with a blow on the head, what are we reading it for? So that it will make us happy, as you write? Good Lord, we would be happy precisely if we had no books, and the kind of books that make us happy are the kind we could write ourselves if we had to. But we need the books that affect us like a disaster, that grieve us deeply, like the death of someone we loved more than ourselves, like being banished into forests far from everyone, like a suicide. A book must be the axe for the frozen sea inside us. That is my belief.

The volume of letters includes other, sometimes humorous, insights into Kafka’s life. In another letter to Pollack in 1902, he tells his childhood friend of his writing desk. Possibly a joke, Kafka claims it has wooden spikes where his knees normally rest.

“If you sit down quietly, cautiously at it, and write something respectable, all’s well,” Kafka writes. “But if you become excited, look out — if your body quivers ever so little, you inescapably feel the spikes in your knees, and how that hurts. I could show you the black-and-blue marks. And what that means to say is simply: Don’t write anything exciting and don’t let your body quiver while you write.”

[H/T Brain Pickings]