Dantalion is described holding a book, and showing many faces of men and women. The book is a small detail with a long background.
Books appear repeatedly in this iconography. The spirit who teaches holds one; the seal itself is a written character; the operator works from a manuscript; the whole tradition is a literate one and knows it. Ritual magic of this kind was never a folk practice. It required Latin, or at least an English translation of Latin, access to expensive manuscripts, the leisure to copy them, and enough education to follow instructions built on astronomical timing and on a technical vocabulary inherited from Agrippa. The people who could do this were clergy, physicians, lawyers, scholars and gentlemen.
This is one of the sharper distinctions in the historiography of European magic, and it is often blurred. Learned ritual magic, grimoires, conjuration, Solomonic material, and the popular witchcraft prosecuted in the trials were different practices, carried on by different classes of people, drawing on different sources. Weyer and Scot both understood the difference and used it: their argument was in part that the illiterate women being burned could not possibly be doing what the learned conjurors claimed to do, and that the conjurors were frauds.
The figure holding a book, then, is a fair emblem for the whole corpus. The Goetia is a text about texts, transmitted by copyists, addressed to readers, and preoccupied with knowledge that was formally taught and formally restricted. Its promises are the promises of a library, offered to people who had noticed how much libraries cost.