Ending the collect

In Paul Turner's Blog by Paul Turner

Q:  GIRM 54 gives 3 options for the end of the collect. Can you explain how these came about? In Latin, almost all the collects just end with simply ‘Per Dominum’ and not the formulas given in GIRM 54. ‘m interested to know how the different endings came about.

A:  Most of the collects end with the first option, but sometimes the prayer mentions Christ near the end, and sometimes the prayer is addressed to Christ. Both circumstances change the ending.
For example, the collect for December 22 is addressed to God but concludes with the words “his company as their Redeemer.” Because the reference to Christ the Redeemer is so close to the conclusion, the second optional ending from GIRM 54 is used, which does not mention Christ, but simply says, “Who lives and reigns with you.”
The collect for the morning mass on December 24 is addressed to Jesus Christ, which is very rare. So it uses the third option from GIRM 54. The conclusion “Who live and reign” does not mention Christ because the conclusion is addressed to him.The form of the verbs also changes because the other collects mention Christ in the third person (“Who lives and reigns”) but this one uses the second person (“[You]” Who live and reign).