This dissertation studies the uses of silence in a corpus of Baroque poems about portraits and funerary monuments. I explore silence as a dynamic, dialogic space where poetic voice, implicit reader and work of art interact. Within these poetic texts --written between 1599 and 1650 by poets from Francisco de Rioja to Quevedo or Góngora-- I focus on the question of representation: how, in ekphrastic texts, silence--whether the silence of the poet or that if the object he is describing--reveals certain anxieties about representation. Using enargeia --lifelike vividness--the Baroque poet searches for a new poetic art in which the `speech' of the portrayed breaks the ultimate silence of death. My critical discussion is rooted in an extensive corpus of seventeenth-century poems, an awareness of the moral implications of silence in Spanish Baroque philosophy, and in recent theoretical discussion of intermediality and ekphrasis, such as Mitchell's theory of ekphrasis and otherness (1994), and Foucault's concept of heterotopy (1986). My dissertation also examines the role of silence in its relation to the ideas of presence and absence in funerary ekphrasis, which includes the poetical description of tombs, as well as in the genre of laudatory ekphrasis and the poetical epitaph. I analyze the relationship between these instances of ekphrasis and the visual representations of silence in several books of emblems by Alciato, Kircher, and Vaenius, published in Europe between the sixteenth and seventeenth centuries. My dissertation demonstrates how silence is a central concept of Baroque aesthetics that identifies fictional representation with a "teacher of truth," and functions as a vehicle for the acquisition of moral knowledge in the context of the Baroque idea of desengaño, thus siding with the objectives of the Spanish Counter-Reformation.