The Adornment Of The Spritual Marriage by John of Ruysbroeck
CHAPTER X. OF INWARDNESS
From this unity springs inwardness; for none can be inward save him who is gathered together in unity within himself. Inwardness means that a man is turned within, into his own heart, that thereby he may understand and feel the interior workings, and the interior words of God. Inwardness is a sensible fire of love, which the Spirit of God has blown to a flame, and which urges a man from within; and he knows not whence it comes nor what has befallen him.