As yet the soul remains cold and hard, for although the sun grows warmer, it is yet far from summer's clear and genial light. But soon all is changed. The divine sun begins to do its heavenly work in the well-prepared garden of the soul.
When, therefore, the genial sun of God's grace begins to shine brightlyu upon this well-cultivated garden all the sou'ls inner and outer faculties being fully prepared all its higher and lower tendencies directed towards heaven, then indeed the sweet flowers of May gein to bloom, and all the welcome gifts of summertime. The eternal God causes the soul to blossom forth and to produce good fruit of virtue; and the joy in that soul no tongue can tell. For now the Holy Spirit is there, and his brightness shines directly upon the soul, yea, into its inmost depths. Well may he now be called the true Comforter, since his influence is so delicious. O how great a joy! O how rich a feast, the sweet odors of whose nourishing food excite the souls deepest longing! These are granted in every plenty of enjoyment to the rightly prepeared soul by the gentle Spirit of God. One drop of his divine comfort is worth more than all the joys of created things put together; and it overpowers and quenches all longing for them whatsover.
When a man feels this action of the divine comforter so wonderfully great and so unexpected, he would gladly sink down into its depths and rest and slumber in it for ever. He feels like Saint Peter at the Lord's Transfiguration; it is good for him to be there, and would set up three tabernacles of joy out of one drop of the happiness now granted him, and there dwell for ever. - Father John Tauler, O.P. (from today's Magnificat
You can read more about the Transfiguration here.