In this essay I argue - on the basis of several well-known scenes in the Arena Chapel (Joachim Among the Shepherds, Annunciation to Anna, Raising of Lazarus, Kiss of Judas, Last Judgment) - that Giotto's celebrated "wit", or ingegno, consisted in far more than the shrewd humor attributed to him by Trecento sources. In analogy to the Plinian artistic virtue of ingenium (the ability to suggest more than is depicted), Giotto's wit was also the specifically pictorial resourcefulness that enabled him to use the devices of a newly-perfected illusionism (foreshortening, lost profiles, effects of illumination) to evoke "invisible" realities. In support of this interpretation, I refer Cennino Cennini's definition of painting as an art of "cloaking" the unseen in the "shadow" of appearances, to the dematerialization of the surface of representation achieved by early Trecento modeling practices. The Arena Chapel as a whole may be viewed as a "theater of illusion" for the staging of the individual beholder's journey towards salvation. I suggest that Giotto's visualizations of the invisible had a fruitful afterlife; we should be attentive to their persistence in the art of the Quattro- and Cinquecento, since they play an especially powerful (though frequently overlooked) part in the "animation" of narrative sequences.