Through a series of circumstances and research I’ll explain later, I was at the University of Washington library's Special Collections Book Arts and Rare Book Collection, meeting its curator. Unrelated to the topic at hand, I ask offhandedly if they have any Whitman. In fact, they have a very fine concentration of Whitman editions, including a first edition of a book I have particular interest in, November Boughs, which he published in 1888 after his health broke.
She pulled three editions, including that first one, and said there was something special: Whitman had written an inscription and signed it. (J.G. Milligan appears to be a fellow Brooklynite of Whitman’s from my quick research.)
I always think of these kinds of links from one person to the next: having held a book the edition of which Whitman not only wrote and for which he supervised the printing, but also held this particular copy, it's like forging a connection back to his time. He's no longer such a distant historical figure.