She does not recognize that in Dee's arguments for a divine and Christian rationale behind his operations lies a rhetoric (and a set of biblical topoi) already much worn by use. Although she cites Stephen Clucas' recent work on the precedents for Dee's practices in medieval Solomonic magic, she largely ignores its implications; at any rate she does not pursue his leads and does not seem to have looked closely at most of the texts he cites.
The assumption that Dee's practices are original with him, or at the very least must harbor early modern principles (as opposed to medieval principles or precedents) sometimes leads her to misread the evidence. So, for example, Harkness writes:
In Dee's time ... Reformation theologians placed a new emphasis on the ways in which prayer could foster an "unmediated relationship between the individual and God." Dee showed himself, in this respect at least, very much a Protestant, for he did not direct his prayers to intercessory agents .... He communicated with God directly, and asked the Deity to send angels, who would then function as intermediaries in the transmission of divine knowledge. (125)
However addressing God in order to request the presence of angels to deliver information is a standard procedure of such operations, having little to do with the Reformation or Protestant theology. In medieval texts like the Ars notoria and its avatars, and in fact in those crystallomantic experiments intended to bring down angels (whose prayers differed in no fundamental aspect from orthodox Christian prayers, or for that matter, from Dee's), God is typically addressed directly and is similarly requested to send angels as intermediaries in the transmission of knowledge. (See for example the crystallomantic experiments numbered 24 and 25 edited by Kieckhefer in Forbidden Rites [Stroud, Gloucestershire: Sutton Publishing, 1997], 244-245). Harkness' unfamiliarity with the medieval traditions of theurgy leads her to overstate as well the distinction between "magical invocation" and "prayer." She writes: "In prayer, the practitioner subjects himself to the will of God. In magical invocation, on the other hand, the practitioner subverts the hierarchical arrangement of the cosmos by asserting his or her will over a spirit and, through a subsequent binding spell, controlling a spirit's actions."(120)
Yet in practice few texts show more consciousness of the hierarchical arrangement of the cosmos than those devoted to conjuring spirits. All use prayer; even necromantic rituals often show a fine sensitivity to the order in which lower spirits must be bound by loftier ones, and it is generally recognized in one way or another that the whole machine moves at the will of God. While is not clear in all cases whether the spirits involved in necromantic experiments are good, bad, or simply neutral, in those experiments and texts explicitly devoted to the invocation of angels, the angels are typically not "bound" or coerced in the way that demons are -- as Dee clearly knew himself, their presence was requested through humble petition to God.
Other bald generalisations about practices commonly characterised as "magical" obscure their possible relevance to Dee's enterprise. Harkness writes: "In late medieval and early modern Europe stones were used in divination typically to locate stolen property, a practice decried by the church." (117) While it is true that the immediate point of many kinds of divination is the location of stolen property (or hidden treasure), it is also true that medieval texts which actually describe the prayers and rituals accompanying the use of crystal stones show a somewhat broader and more interesting array of spiritual concerns and sensitivities than such a characterization might suggest. In fact, even in respect of using the crystal to locate hidden treasure, Dee's work is hardly unusual, for Dee himself was wont to use the crystal to ask questions about hidden treasure whenever his financial fortune was at a low ebb (as Harkness notes in another location). Doubtless Dee had other concerns as well; but so too, sometimes, did medieval conjurers of angels, whose aims and motivations were sufficiently close to Dee's to warrant further and more detailed comparison of their prayers and practices to Dee's. While it is probably true that Dee's concerns in his angelic conversations differed in certain ways from those of the medieval predecessors, Harkness is not really sufficiently aware of the medieval practices to make authoritative statements about what these differences are.
Review of John Dee's Conversations with Angels: Cabala, Alchemy, and the End of Nature