Why the gift of a library as the central conceit of the book?

To quote Thomas Connell (President of Desert Wells College), in his introductory note to Appendix C, The Gilmartin Jacobsen Donation: Bibliography of a Mind

 "A personal library says a lot about its owner. Not just in terms of specific books and titles but also, to use a concept from my own background, ‘archaeologically,’ in the successive layers that emerge over time to show the growth and direction of the maturing mind."
In other words, a personal library not only represents the taste and dispositions of the reader responsible for creating it in the first place. It embodies his or her mind. 
Or as Gilmartin Jacobsen explains in his remarks in the first dialogue, Now & Then (p. 22):
"As I was packing it up, I was struck by the thought that it’s also a schematic of one mind. It’s made up of thousands of data clusters that represent millions of data points aligned (and realigned) by the charge my unique electrical field at one time or another over the course of 50 years or so. Each book as a touchstone reminded me of a specific time and place and, often, emotion or desire or need, that colored its acquisition. Like that uncut Thucydides for which, after all, you can find better translations and cheaper editions. Each book tells the story about me, about my progress over the years from ignorance to enlightenment, resistance or confusion or simply befuddlement to acceptance, incorporation, and appreciation. Call that the Arc of my Ultimate Self-Relevance. More important, though, the ‘me’ standing before you is somehow composed of all the books in the library I’m entrusting to your care. If my biological DNA happens to contaminate their covers and pages, then their content somehow forms my intellectual DNA encoded and transmitted by each volume. Viewed as a collection, as a library, these books reflect the emerging, evolving aesthetic dimension of the life of my mind."

I couldn’t have said it better myself. 

Jacobsen’s library is the perfect matrix for a discussion of the role of a liberal education in the 21st century, when the relevance of physical books and their atomic bits is seemingly challenged by the emergence of electronic books and their digital bytes. But it’s more than a question of “form.” It strikes at the heart of the notion of “content”: the epistemological basis of knowledge and reality in an age controlled by “the new” and “the now.” 

And finally, there’s the very human aspect of a dying man bequeathing the only significant vestige of his life — his “words and works” as Joshua Cryst puts it in Thema— the books he's read that underwrite the things he's done and said.