When Tycho Brahe published a description of his astronomical instruments in 1598 as part of a strategy to procure royal patronage, it was not with one of his grander, precision measurement tools that he opened his account, but rather a small brass quadrant with limited observational utility. The defining feature of this instrument was seemingly a small emblematic image inscribed within the arc of the quadrant. Through this symbolic motif Tycho conveyed a moralising message about the relative worth of astronomy. Considering a range of visual productions that may have influenced his iconography, the present paper situates the quadrant within the broader context of Renaissance visual culture and examines the significance of the quadrant in Tycho's wider instrument collection.