The Adornment of the Spiritual Marriage, by Jan van Ruysbroeck, , at sacred-texts.com
When, however, this coming and this degree are granted to such men as first begin to turn from the world; even though their conversion be perfect, and they have abandoned all worldly consolation, that they may be wholly God's, and may live altogether for Him,yet they are still feeble and have need of milk and sweet things, and not of the strong food of fierce temptation and the loss of God. And in this season, that is to say, in this state, hoar-frost and fog often harm such men; for it is just in the middle of May according to the course of the inward life. Hoar-frost is the desire to be somewhat or the belief that one is somewhat; or to be attached to one's self, or to suppose that we have earned these consolations and are worthy of them. This is hoar-frost, which may destroy the flowers and fruits of all the virtues. Fog is, the desire to rest in inward consolations and sweetness. This darkens the air of the reason; and the powers, which ought to open and flower, close again. And thereby one loses the knowledge of truth, and yet may keep a certain false sweetness, which is given by the devil, and which in the end shall lead us astray.