Abba Philimon
Abba Philimon, who apparently lived around the sixth century in Egypt.  Except for
one text (part of which is excerpted here), there are no other writings by Abba
Philimon and we have no other references to him beyond the text itself.  However,
his text is important for its long passages on inward meditation and watchfulness.  
It is also interesting to note that the Jesus Prayer is first cited by Abba Philimon in
the form we know it today: "Lord Jesus Christ, Son of God, have mercy upon me."
A brother named John came from the coast to Father Philimon and, clasping his feet,
said to him: "What shall I do to be saved?  For my intellect vacillates to and fro and
strays after all the wrong things."  After a pause, the father replied: "This is one of
the outer passions and it stays with you because you still have not acquired a
perfect longing for God. The warmth of this longing and of the knowledge of God has
not yet come to you."  The brother said to him: "What shall I do, father?"  Abba
Philimon replied: "Meditate inwardly for a while, deep in your heart; for this can
cleanse your intellect of these things."  The brother, not understanding what was
said, asked the Elder: "What is inward meditation, father?"  The Elder replied: "Keep
watch in your heart; and with watchfulness say in your mind with awe and trembling:
"Lord Jesus Christ, have mercy
upon me."  For this is the advice which the blessed Diadochos gave to beginners."

The brother departed; and with the help of God and the Elder's prayers he found
stillness and for a while was filled with sweetness by this meditation.  But then it
suddenly left him and he could not practice it or pray watchfully.  So he went again
to the Elder and told him what had happened.  And the Elder said to him: "You have
had a brief taste of stillness and inner work, and have experienced the sweetness
that comes from
them.  This is what you should always be doing in your heart: whether eating or
drinking, in company or outside your cell, or on a journey, repeat that prayer with a
watchful mind and an undeflected intellect; also chant, and meditate on prayers and
psalms.  Even when carrying out needful tasks, do not let your intellect be idle but
keep it meditating inwardly and praying.  For in this way you can grasp the depths of
divine Scripture and the power hidden in it, and give unceasing work to the intellect,
thus fulfilling the apostolic command: "Pray without ceasing" (I Thessalonians 5:
17).  Pay strict attention to your
heart and watch over it, so that it does not give admittance to thoughts that are evil
or in any way vain and useless.  Without interruption, whether asleep or awake,
eating, drinking, or in company, let your heart inwardly and mentally at time be
meditating on the psalms, at other times be repeating the prayer, "Lord Jesus Christ,
Son of God, have mercy upon me."  And when you chant, make sure that your mouth
is not saying one
thing while your mind is thinking about another."
Again the brother said: "In my sleep I see many vain fantasies."  And the Elder said
to him: "Don't be sluggish or neglectful.  Before going to sleep, say many prayers in
your
heart, fight against evil thoughts and don't be deluded by the devil's demands; then
God will receive you into His presence.  If you possibly can, sleep only after reciting
the psalms and after inward meditation.  Don't be caught off your guard, letting your
mind admit strange thoughts; but lie down meditating on the thought of your prayer,
so that when you sleep it may be conjoined with you and when you awake it may
commune
with you (Proverbs 6:22).  Also, recite the holy Creed of the Orthodox faith before
you fall asleep.  For true belief in God is the source and guard of all blessings."  
[1] from G. E. H. Palmer, Philip Sherrard, and Bishop Kallistos Ware, trans., "The
Philokalia: Volume II," (London: Faber and Faber, 1981), pp. 347 – 348.
Lives of the Saints