The French Carmelite Père Joseph de Saint Marie, OCD, in some of his conferences on St. Teresa and in his book Notre Dame du Mont-Carmel remarks about the fact that many of the significant events in St. Teresa's life happened on or around the feast of the Assumption. Her vision of hell, which inspired her to begin the monastic reform, occurred in the month of August, as did the foundation of St. Joseph's monastery in Avila. Two magnificent visions of Our Lady took place, in different years, on August 15. In her Life, St. Teresa describes the visions. Of the first one she writes:
...In a rapture there was pictured to me [Our Lady's] ascent into Heaven and the joy and solemnity with which she was received in the place where she now is. To explain how this happened would be impossible for me. Exceeding great was the glory which filled my spirit when it saw such glory. The fruits of the vision were wonderful and I was left with a great desire to serve Our Lady, because of her surpassing merits....In the second apparition, which occurred on August 15, 1561, St. Teresa found herself transfigured, with Our Lady on her right and St. Joseph on her left. They clothed her in a mantle of great "whiteness and brightness," which meant she was "cleansed of [her] sins." According to St. Teresa's autobiography: "Our Lady suddenly took me by the hands and told me that I was giving her great pleasure by serving St. Joseph and that I might be sure that all I was trying to do about the convent would be accomplished and that both the Lord and they would be greatly served in it." Our Lady gave her a jeweled cross on a golden chain (similar to that of an abbess) signifying the saint's authority as a mother foundress. The vision left St. Teresa feeling "greatly comforted and full of peace." In such mystical experiences the strong Marian aspect of the Carmelite charism was once again emphasized, as a witness for those who would come after.
(All quotations from Msgr. Doheny's Selected Writings of St. Teresa)