These materials are subdivided into five categories: calculations, lectures, letters, manuscripts, and miscellaneous. These handwritten materials appear to be the earliest drafts of Sellars's philosophical works, which were later dictated to a secretary. Due to the nature of Sellars's handwriting, this material is rather difficult to decipher. However, these materials could provide researchers with insight into Sellars's thought processes. Most of these notes are written on yellow legal pads and vary in length from a few sheets to an entire tablet's worth of notes. When possible, the files are arranged alphabetically by published title. Sometimes Sellars supplied the title, but more commonly the titles are archivist assigned. More specific descriptions of each of the five categories are listed below.