My most prized D&D possession is the 1983 World of Greyhawk boxed set that I bought new when I was thirteen. The two booklets, the map, and the box itself remain in terrific (VG+) condition—which amazes me given that the map adorned my bedroom wall for five of my teenaged years. Especially when compared to books like my battered first edition PHB (which looks like it’s been to the bottom of the Abyss and back), it’s more than a minor miracle that it’s in such good shape.
Moreover, as opposed to the bulk of my AD&D books that are boxed and in the garage, the Greyhawk boxed set is on a table in the study (with other legacy Greyhawk content) alongside the 5e rule books, because it’s still in active use. I consider it to be my Greyhawk ur-text, the definitive, canonical source from which all the lore in my setting springs, and I consult it regularly.
It just so happens that almost two weeks ago (on the 13th) I broke down and purchased the PDF version. It’s more convenient for a host of reasons, but, when I use it, I feel dirty, like I’m cheating on the physical copy. I obviously have issues.