St. John of Sinai. "The ladder of Divine ascent".
Step 7. On mourning which causes joy.
29. When we see anger and pride in those who seem to be mourning in a way pleasing to God, then their tears are to be regarded as a repugnant to God. For what fellowship has light with darkness? (2 Corinthians vi, 14.)
30. The fruit of morbid compunction is self-esteem, and the fruit of meritorious compunction is consolation.
31. Just as fire is destructive of straw, so are pure tears destructive of all material and spiritual impurity.
32. Many of the Fathers say that the question of tears, especially in the case of beginners, is an obscure matter and hard to ascertain, as tears are born in many different ways. For instance, there are tears from nature, from God, from adverse suffering, from praise worthy suffering, from vainglory, from licentiousness, from love, from the remembrance of death, and from many other causes.
33. Let us, stripped by the fear of God, train ourselves in all these ways, and acquire for ourselves pure and guileless tears over our dissolution. For there is no dissimulation or self-esteem in them, but on the contrary there is purification, progress in love for God, washing away of sin and the sublimation of the passions to dispassion.
34. It is not surprising if mourning begins with good tears and ends with bad. But it is praiseworthy if reprehensible and natural tears are sublimated to spiritual tears. People inclined to vainglory understand this problem clearly.
35. Do not trust your fountains of tears before your soul has been perfectly purified. For wine cannot be trusted when it is drawn straight from the vats.
68. Our enemies are so wicked that they turn even the mothers of virtues into the mothers of vices, and those things which make for humility, they make into a cause for pride. Frequently the very setting and sight of our dwellings are of a nature to rouse our mind to compunction. Let Jesus, Elijah and John who prayed alone convince you of this. I have often seen tears provoked in cities and crowds to make us think that crowds do us no harm and so draw nearer to the world. For this is the aim of the evil spirits.