This dissertation takes the emblem as the starting point for an investigation of the use of vivid imagery as an aid to memory, reason, and the will in sixteenth- and seventeenth-century literature and society. The emblems of Andrea Alciato can best be understood as a collection of visual commonplaces, by analogy to Erasmus' collection of adages. In this new model for emblematic signification, use of an emblem asserts a relationship not only between signifier and signified, but between the present use and past uses of that motif. This destabilizes the distinction, common in scholarship, between natural and conventional signs, and between symbol and allegory. The rhetorical potency of emblems and other visual means of communication was credited in the period to the principle of enargeia: setting ideas "before the eyes" in vivid, often violent terms. This results in a visual space crowded with shocking imagery set in striking combinations: a decorum of indecorum. Visual commonplaces share much in common with the imagined agents of the mnemotechnical tradition; preserved through the ages by virtue of their capacity to act upon consciousness, they function as mental machines and as fundamental units of culture. Moralists in the Renaissance sought to harness this power to didactic ends. In the Moriae encomium, Erasmus offers the figure of Silenus as an exegetical key. Jacob Cats employs not simply emblems, but the recursive reinterpretation of emblems to engender moral reformation. John Donne provokes thought with the shock tactic of paradox. (Dissertation Abstracts)