Psalm 139 says it well!
I was preparing to give a little presentation to the group of Secular Franciscans with whom I serve.
The topic was the Liturgy of the Hours. I wanted to go into the meaning and history of this Prayer of the Church, as well as help remind people of some of the practical principles involved.
One detail we discussed was posture and gestures. Rather than just saying: “This is what we do. THE END.” I wanted to explain the meaning for these physical aspects of our liturgical prayer.
Not being an expert myself, I did a little research. Although my sources were geared toward the Liturgy of the Eucharist, the meaning, history and symbolism would be applicable to the Liturgy of the Hours as well.
They listed other postures/gestures used at Mass (such as kneeling, processing, etc.), but I just picked out those pertinent to our topic of the Office. You may find the explanations interesting.
STANDING In standing, we show respect and honor. We especially stand during the Gospels in reverence; they contain the words of Jesus. This has been a common prayer custom since the early church. It is the stance of those who have risen with Christ and seek the things that are above. In standing we acknowledge our full stature given by God. During the common recitation of the office, we stand for the introductory prayers and hymn and then for the Gospel canticle and what follows.
SITTING: Sitting is the posture of listening and meditation. We sit for the psalms, reading, and responsorial.
BOWING is a sign of profound reverence. You might notice people bowing during the “Glory to the Father” and at the name of Jesus, etc.
THE SIGN OF THE CROSS “is a simple ritual which expresses our prayer that the Trinity–God the Father, Son and Holy Spirit–will be with us.” (Schiffer)
“Because it was by his death on the Cross that Christ redeemed humankind, we trace the Sign of the Cross on our foreheads.” (USCCB) We make the sign of the Cross at the beginning of the Gospel Canticle (While saying: “Blessed be the Lord, the God of Israel” / “My soul proclaims the greatness of the Lord.” We also make it at the beginning and the end of the Office.
Excerpts and information from: