Prayer vs. Presumtion - John of Karpathos

12. Sometimes people find themselves brightly illuminated
and refreshed by God's grace for a while,
but then this grace may be taken away,
and they can fall into depression and start grumbling
and even give up dispiritedly
instead of energetically renewing their prayers
to call down again that assurance of salvation.
Such behavior is like an ungrateful beggar
taking alms at the palace door
and then walking off indignantly
because he was not invited in
to dine with the king himself.

- John of Karpathos

Mindfulness of Death - St Philotheos

6. The first gate of entry to the noetic Jerusalem - that is, to attentiveness of the intellect - is the deliberate silencing of your tongue, even though the intellect itself may not yet be still. The second gate is balanced self-control in food and drink. The third, is ceaseless mindfulness of death, for this purifies intellect and body. Having once experienced the beauty of this mindfulness of death, I was so wounded and delighted by it - in Spirit, not through the eye - that I wanted to make it my life's companion, for I was enraptured by its loveliness and majesty, its humility and contrite joy, by how full of reflection it is, how apprehensive of the judgment to come, and how aware of life's anxieties. It makes life-giving, healing tears flow from our bodily eyes, while from our noetic eyes rises a fount of wisdom that delights the mind. This daughter of Adam - this mindfulness of death - I always longed, as I said, to have as my companion, to sleep with, to talk with, and to enquire from her what will happen after the body has been discarded. But unclean forgetfulness, the devil's murky daughter, has frequently prevented this.

- St Philotheos of Sinai, Forty Texts on Watchfulness, The Philokalia Vol. III

John Klimakos - Three Chapters on Prayer

56. When you go out after prayer,
keep your tongue under restraint,
for it is well capable of dissipating,
in a very short time,
what you labored to gather together.

57. When you are ready to stand
in the presence of the Lord,
let your soul wear a garment woven throughout
from the cloth of our forgiveness of others.
Otherwise your prayer will be of no value whatsoever.

58. Let all your prayer be completely simple.
Both the tax collector and the prodigal son
were reconciled to God by one simple phrase -
one said: God, have mercy on me, a sinner,
and the other: Father, I have sinned against you.

- St John Klimakos