Our Eucharist (communion) liturgy begins with a Collect (short prayer) for Purity. Here it is in the traditional 1928 version:
Almighty God, unto whom all hearts are open, all desires known, and from whom no secrets are hid; Cleanse the thoughts of our hearts by the inspiration of thy Holy Spirit, that we may perfectly love thee, and worthily magnify thy holy Name; through Christ our Lord.
Here is the same prayer in the new (2019) ACNA Book of Common Prayer version:
Almighty God, to you all hearts are open, all desires known, and from you no secrets are hid: Cleanse the thoughts of our hearts by the inspiration of your Holy Spirit, that we may perfectly love you, and worthily magnify your holy Name; through Christ our Lord.
The most obvious change is the replacement of “thee” and “thy” with “you” and “your.” “Thee” and “thy” sound archaic and formal to many people, which conceals the fact that as originally written they were intended to sound informal and familiar (“you” was the formal mode of address), building on Jesus’ admonition to address Almighty God in a familiar way as “our Father.”
The first clause is changed in form, probably to emphasize that it is an address to God, not simply a description of God’s attributes. Interestingly, the authors of the 2019 book have chosen to retain the old-fashioned word “magnify,” which here means to praise or glorify.
In both the 1928 or 2019 versions, the purpose of the prayer is the same. It focuses the mind on the need for purity of thought when approaching the holy God. The prayer begins by acknowledging that God knows all of our thoughts, which should trigger the realization that our thoughts, distracted as they so often are, are not worthy of God’s greatness. But the prayer turns immediately to a petition that God’s Holy Spirit will help us be worthy. This theme of submission to God’s power runs through the whole liturgy and reminds us of our dependence on God’s free gift of himself in giving us life and in sending his son, Jesus, to save us from our sins.