How charming is divine philosophy!
  Not harsh, and crabbed, as full fools suppose,
    But musical as is Apollo's lute...

                Milton, Mask of Comus (l. 476)

Dionysius the Pseudo-Areopagite St John of the Cross Walter Hilton Richard Rolle Thomas a Kempis Jacob Boehme Nicholas of Cusa

Paul Tillich Soren Kierkegaard Thomas Merton Henri Nouwen

Soren Kierkegaard

"Just as in earthly life lovers long for the moment when they are able to breathe forth their love for each other, to let their souls blend in a soft whisper, so the mystic longs for the moment when in prayer he can, as it were, creep into God."

"The function of prayer is not to influence God, but rather to change the nature of the one who prays."

“Do you not know that there comes a midnight hour when every one has to throw off his mask? Do you believe that life will always let itself be mocked? Do you think you can slip away a little before midnight in order to avoid this? Or are you not terrified by it? I have seen men in real life who so long deceived others that at last their true nature could not reveal itself;... In every man there is something which to a certain degree prevents him from becoming perfectly transparent to himself; and this may be the case in so high a degree, he may be so inexplicably woven into relationships of life which extend far beyond himself that he almost cannot reveal himself. But he who cannot reveal himself cannot love, and he who cannot love is the most unhappy man of all.”

“It is so hard to believe because it is so hard to obey.”

“Purity of heart is to will one thing.”

“Love does not alter the beloved, it alters itself.”