St Symeon the New Theologian (949-1022) spent most of his life in Constantinople, where he was the abbot of St Mamas. The title "Theologian" (referring in this context to a highly evolved mysticism and definitely not to an ability to write dense books with lots of footnotes) is given in Orthodoxy to only two other saints: John the Evangelist and Gregory Nazianzen. He combined a most intense mystical life with a very rigorous asceticism. His feast is variously celebrated on March 12 or October 12.

The Eucharist, along with a frequent and worthy reception of the same, occupies a crucial place in his spirituality. Of the following three quotes, the first (a communion prayer) is found on pp 60-61 of Kallistos Ware The Inner Kingdom (SVS Press 2000). The following two come from, respectively, On the Mystical Life and Hymn 15.

Rejoicing at once and trembling,
I who am straw receive the Fire
And, strange wonder!
I am ineffably refreshed
As the bush of old
Which burned yet was not consumed.

The Son of God cries out plainly that our union with Him through communion is such as the unity and life which He has with the Father. Thus, just as He is united by nature to His own Father and God, so we are united by grace to Him, and live in Him by eating His flesh and drinking His blood.

We become members of Christ--and Christ becomes our members,
Christ becomes my hand, Christ my foot, of my miserable self,
and I, wretched one, am Christ's hand, Christ's foot!
I move my hand, and my hand is the whole Christ
since, do not forget it, God is indivisible in His divinity;
I move my foot, and behold it shines like that one!
Do not say I blaspheme, but welcome such things,
and adore Christ who makes you such!
Since, if you so wish you will become a member of Him,
and similarly all our members individually
will become members of Christ and Christ our members,
and all which is dishonorable in us He will make honorable
by adorning it with His divine beauty and His divine glory,
and living with God at the same time, we shall become gods,
no longer seeing the shamefulness of our body at all,
but made completely like Christ in our whole body;
each member of our body will be the whole Christ
because, becoming many members, He remains unique and indivisible,
and each part is He, the whole Christ.