Exercitatio veneranda sanctae devotionis, Domine,
tuorum fidelium corda disponat,
ut et dignis mentibus suscipiant paschale mysterium,
et salvationis tuae nuntient praeconium.
This prayer was in the Gelasianum Vetus for this same day. It was not in the pre-Conciliar Missal: Exercitatio ueneranda, domine, ieiunia salutaris pupuli tui corda disponat, ut et dignis mentibus suscipiat pascale mysterium et continuate deuotionis sumat augmentum: per. Yes, I wrote it correctly. The Redactors saw fit to make changes, as you can see. First, sancta devotio replaced ieiunia salutaris and tui fideles replaced populus tuus.
Exercitatio is "exercise, practice". Dispono, means basically "to place here and there, to set in different places, to distribute regularly, to dispose, arrange". There is a military overtone to the word as well, "to set in order, arrange, to draw up, array a body of men, a guard, military engines". Praeconium signifies, "of or belonging to a praeco or public crier: quaestus, the office or business of a public crier", thus, "a crying out in public; a proclaiming, spreading abroad, publishing". We have raked over devotio a few times already in the previous weeks, so you can use the little search engine on the left bar of the blog to find previous references. Suffice to say that devotio is a tough word which in this context means more or less "religious undertaking". It can sometimes even mean celebration of the Eucharist itself. Suscipio is "to take upon one, undertake, assume, begin, incur, enter upon (esp. when done voluntarily and as a favor; recipio, when done as a duty or under an obligation)."
May the venerable exercise of this holy undertaking, O Lord,
dispose the hearts of Your faithful,
so that they may enter into the paschal mystery with worthy minds
and announce the message of Your salvation.
Since we are past the half way point in Lent, there has been a shift in the prayers, I think. There is a focus on the coming Triduum now. The vocabulary today with paschale mysterium and praeconium point to the Triduum and Vigil. Praeconium makes you think right away of the great chant of the deacon called the Exsultet, or Praeconium Paschale. The Redactors chose to strip the prayer of it older content, in the replacement of "fasts" (ieiunia) with devotio.
We will verify this in the days to come.