 Another noteworthy feature of Shaftesbury interpretation is his use of illustrations. Shaftesbury worked on numerous allegorical illustrations for the second edition of Characteristics, putting tremendous effort into both the overall plan and the minute details of these illustrations and engaging in extensive correspondence with the artists he hired to execute the pictures. He seemed to want his audience to read the illustrations as carefully as the words, their meanings (some readily apparent, others subtle to the point of hiddenness) essential to a full understanding of the text. (The fullest discussion of the illustrations is Paknadel 1974. Rivers 2000a and Müller 2010, 2012, and 2013 also shed light on how the illustrations interact with and enhance the message of Shaftesbury’s text.) Shaftesbury took care, as well, to compose the marginal headings and index to Characteristicks, and his choices in those places can also be cited as evidence for certain interpretative views (see Rivers 2000b). Characteristicks was one of the earliest books in English to have an index.