Two kinds of prayer…

Such is the difference between the two kinds of prayer. The water running through the aqueducts resembles sensible devotion, which is obtained by meditation. We gain it by our thoughts, by meditating on created things, and by the labour of our minds. In short, it is the result of our endeavors, and so makes the commotion I spoke of, while profiting the soul. The other fountain, like divine consolations, receives the water from the source itself, which signifies God.
–Saint Teresa of Avila (1515-1582)

By contemplation…

By meditation, the soul walks afoot with labor; by contemplation, it flies without trouble. Thus Saint Teresa said, that when God had admitted her to this sort of prayer, her difficulties ceased at once, and she experienced a powerful attraction towards acts of all virtues, attended with a marvellous relish and sweetness.
–Louis Lallemant  (1578–1635)

Boundaries of prayer…

When your mind, inflamed by longing for God, little by little divests itself of flesh, as it were, and turns away from all thoughts engendered by sensory impressions, or from memory, being at the same time full of adoration and rejoicing, then you may conclude that it has approached the boundaries of prayer.
–Saint Nilus of Sinai (d. 430)

This repose of the soul in God…

“O amiable Goodness!”  “O infinite Charity!”  “O my God and my All!”  “O supreme Sweetness!” Make these aspirations, or any others, as God will inspire you; but remember that if, in making one of these short prayers of love, your soul regain her peace and recollection in God, it is unnecessary to make a second; continue, rather, this silence, this repose of the soul in God, which includes excellently all the acts that we can ever make.
–Saint Paul of the Cross (1694-1775)