Prostrations and Bows
μετάνοια — metania · meh-TAH-nee-ah
In brief
Orthodox prayer involves the body: bows of the head, bows from the waist, and full prostrations with knees and forehead to the floor. The bow is called a metania — from the Greek word for repentance — because bending the body is meant to bend the heart. Prostrations have their seasons: they fill Great Lent, and they are set aside on Sundays and through the fifty days from Pascha to Pentecost.
Three movements
Orthodox worship uses a small grammar of gestures, from lesser to greater. The simplest is a bow of the head, made constantly through the services — at blessings, at the name of the Trinity. Next is the small bow, or metania: the worshipper makes the sign of the cross and bows from the waist, the right hand reaching toward the floor. Greatest is the full prostration (the "great metania"): down on both knees, palms and forehead touching the floor, then immediately back up to standing.
That last part matters. You go down only in order to stand back up; a prostration completed is a miniature of the whole Gospel — fallen, and raised. The very name teaches the same lesson: metania comes from metanoia, repentance, the turning-around of the mind. The body is not decoration in Orthodox prayer; bowing it is one of the oldest ways of teaching the heart to bow. In Gethsemane the Lord Himself prayed fallen on His face (Matthew 26:39).
When they are prescribed
The home of the prostration is Great Lent. At the weekday Lenten services the Prayer of St. Ephrem is read with a full prostration after each of its petitions — in the common practice, three prostrations, and in many uses twelve small bows besides. The Great Canon of St. Andrew is sung with bows or prostrations at its refrain, and at the Liturgy of the Presanctified Gifts the faithful make full prostrations as the already-consecrated Gifts are carried past. Lent begins with mutual prostrations at Forgiveness Vespers, each asking the other's forgiveness.
Prostrations also attend the veneration of the Cross — at the Exaltation in September and on the third Sunday of Lent, where most uses appoint prostrations before the Cross even though the day is a Sunday. And beyond the service books, many Orthodox Christians keep a few prostrations in their private evening prayers year-round, a practice best undertaken with a priest's guidance rather than by private ambition.
When they are omitted, and why
Just as deliberately, the tradition sets prostrations aside. On Sundays, on great feasts, and through the fifty days from Pascha to Pentecost, kneeling and prostrations give way to standing — the posture of resurrection. The rule is ancient: the First Ecumenical Council at Nicaea (325) directed that on the Lord's Day and in the days of Pentecost prayer be made to God standing, and long custom extended the same joy-keeping to prostrations. The season of standing ends only at Vespers of Pentecost, when the Church kneels again for the feast's "kneeling prayers."
Practice varies in the details — Greek and Slavic service books do not agree on every bow, parishes differ, and jurisdictions inherit different customs; where the books and the parish differ, follow the parish. The variation is not a scandal, because the gestures are servants, not masters. Those whose knees or health do not allow prostrations lose nothing before God, and the tradition is unanimous on one point: never measure a neighbor's devotion by the depth of the bow.