The William Ernest Hocking Rare Book Collection represents a portion of the philosopher's personal library that resided at "West Wind," Hocking's 400-acre estate in Madison, New Hampshire. UMass Lowell Professor John Kaag's encountered with these rare editions, from which he drew inspiration, is described in his 2016 book, American Philosophy: A Love Story. After spending weekends inventorying the books, Kaag arranged for a portion of them to be added to UMass Lowell's Special Collections.
Ranging in date from 1637 to the Mid-Twentieth Century the Hocking collection is comprised of over 260 volumes as well as a cache of related documents. Highlights include an early edition of Rene Descartes's Discourse on Method which introduced "I think, therefore I am. (Cogito ergo sum.)” and John Locke’s 1690 work, Two Treatises of Government. The centerpiece is a 1651 first edition of Leviathan by Thomas Hobbes. While many of the books were purchased by Hocking, the collection also includes works previously owned by William James, Josiah Royce, and others. Of particular note, is the marginalia and other jottings that these philosophers left behind, revealing evidence of their thought processes as they studied the texts.