Digitized material consists of historical publications that fit the format and physical condition requirements of the Internet Archive, were in the public domain and/or at a low risk of copyright infringement, and had not been digitized by the Internet Archive, Canadiana, Europeana or The Hathi Trust at the time of selection. The Yolton Collection is a collection of rare books ranging from the seventeenth to nineteenth centuries, collected and donated by John W. Yolton (1921-2005), professor of Philosophy at York University. The collection focuses on early editions by or connected to Scottish philosopher John Locke, the subject of Yolton’s doctoral thesis. His wife, Jean Yolton (nee Sebastian), was pivotal to compiling the collection. She often combed antique bookstores and libraries for editions, and her work resulted in the publication of a definitive Locke bibliography. In 2003 Yolton donated his rare collection of antiquarian books to the university’s special collections. It is considered to be one of the finest in the world. Digitized material represents approximately 30% of total collection.