My PhD dissertation analyses intimacy, spirituality, and communication from the interdisciplinary perspective of theology and literary studies by using as its case study the correspondence between the mystic Jeanne Guyon (1648-1717) and her spiritual companion François Fénelon (1655-1717). The study argues that Guyon combines epistolary theory and Trinitarian theology to develop a communication theory that does not seek to describe the mystical union but to reenact it through the intimacy of the private spiritual correspondence. According to Guyon, the epistolary writing act forces the subject to transcend itself in a movement that imitates the internal commerce of the Trinity.