What’s the most valuable/rare book in here?

What's the most valuable/rare book in here? What's its value/rarity/year published?
What’s the most valuable/rare book in here? What’s its value/rarity/year published?

Not sure it’s the rarest, but certainly the oldest: Jean Gerson’s De Spiritualib[us] Nupciis (On Spiritual Marriage) from about 1470, in Burns Library. Lots more info about it, and a link to the digital version, here: bit.ly/ReallyOldBook. As far as value goes, here’s a worthwhile answer: bit.ly/bc-books-worth.