One day, having a little more leisure... I was praying before the Blessed Sacrament, when I felt myself wholly penetrated with that Divine Presence, but to such a degree that I lost all thought of myself and of the place where I was, and abandoned myself to this Divine Spirit, yielding up my heart to the power of His love. He made me repose for a long time upon His Sacred Breast, where He disclosed to me the marvels of His love and the inexplicable secrets of His Sacred Heart, which so far He had concealed from me. Then it was that, for the first time, He opened to me His Divine Heart in a manner so real and sensible as to be beyond all doubt, by reason of the effects which this favor produced in me, fearful, as I always am, of deceiving myself in anything that I say of what passes in me. It seems to me that this what took place: "My Divine Heart," He said, "is so inflamed with love for men, and for thee in particular that, being unable any longer to contain within Itself the flames of Its burning Charity, It must needs spread them abroad by thy means, and manifest Itself to them (mankind) in order to enrich them with the precious treasures which I discover to thee... "

The Autobiography of St. Margaret Mary
St. Margaret Mary Alacoque