The postmodern revival of interest in apophatic (negative) theology neglects the integrated system of spiritual praxis that undergirds traditional negative theology and therefore has failed to realize its potential to address the postmodern themes of alterity, subjectivity, and ontotheology. Traditional apophatic theology forms one aspect of the Eastern Orthodox system of spiritual practices known as "hesychasm" (from hesycheia, inner stillness). This system comprises several elements: an emphasis on systematic spiritual progress via the "Ladder" of spiritual ascent, an understanding of the self in its relation to God, and the assertion of the radical otherness of God. This dissertation brings these elements of apophatic theology into the ongoing dialogue concerning apophatic theology to address the themes of subjectivity, alterity, and ontotheology. Hesychastic practices produce a transformation of human nature that first eliminates the delusory attachments of natural being, and then reconstitutes the person on the basis of openness, selflessness, and relationality. The dissertation argues that the practices of cataphasis (positive predication), apophasis (negative predication), and the "hyper-" (a prefix that connotes the otherness of God) must be located within this transformative system. This relocation of negative theology makes possible the thinking of a self that is at once substantive and interrelational and of God as at once transcendent Unity and immanent and dynamic (thus evading the charge of reinscribing ontotheology). As a preliminary to this system, the dissertation presents the hermeneutic, anthropological, and providential context of the Ladder of spiritual practices. Hesychasm integrates these contextual elements in a system that provides a total environment for the formation of subjectivity. The dissertation presents and then critiques the contrasting postmodern apophaticisms of Jacques Derrida and Jean-Luc Marion. Derrida's analysis of the impossible, his rejection of the identification of deconstruction with negative theology, and his charge that negative theology remains ontotheological pose serious challenges to negative theology. Jean-Luc Marion attempts to defend negative theology against Derrida's charges by means of his concept of the saturated phenomenon and his phenomenology of excess. In both cases, however, the lack of a system of spiritual transformation limits the effectiveness of their insights.