The Sixteenth Call is one of sixteen calls in John Dee's Claves Angelicae used to work the angels of the four Elemental Watchtowers, earth, water, air and fire, received through the scryer Edward Kelley in 1584 and published in Meric Casaubon's 1659 edition of Dee's spiritual diaries. Dee's own angelic informant, named Illemese in the sessions, describes the nineteen calls together as entrances into the knowledge of the mystical tables. It falls the sixteenth of the sixteen, between the two general opening calls and the nineteenth call, which is recited with the name of whichever of the thirty Aethyrs is worked.
The four Watchtowers are the Great Tables of Dee's system, one for each classical element, each populated with its own hierarchy of angelic names read off a grid Dee recorded from the angels letter by letter. The sixteen calls of this middle group are the corpus's working tools for that hierarchy as a whole; Casaubon's 1659 edition prints them consecutively, in the same parallel format of angelic text and English gloss used for the rest of the forty eight keys, without further subdividing them by individual tablet in the base text itself.
Because this is a single closely grouped set drawn from one manuscript tradition, the sixteen calls share the bulk of their documented history: the same 1584 reception date, the same scryer, and the same first printing. What distinguishes The Sixteenth Call from its neighbors is chiefly its position in that fixed sequence, sixteenth in the group of sixteen, rather than any separately attested content of its own.