From Dom Guéranger's The Liturgical Year.
Although the law of fasting began yesterday, yet Lent, properly so called, does not begin till the Vespers of Saturday next. In order to distinguish the rest of Lent from these four days which have been added to it, the Church continues to chant Vespers at the usual hour, and allows her ministers to break their fast before having said that Office. But, beginning with Saturday, the Vespers will be anticipated; every day (Sundays excepted, which always exclude fasting), they will be said at such an early hour, that when the faithful take their full meal, the evening Office will be over. It is a remnant of the discipline of the primitive Church, which forbade the faithful to break their fast before sunset, in other words, before Vespers or Evensong.
The Church has given to these three days after Ash Wednesday a resemblance to the other ferias of her lenten season, by assigning to each of them a lesson from the Old Testament, and a Gospel, for Mass. We, of course, insert them, adding a few reflections to each. We also give the Collects of these three days.
The station, in Rome, for the Thursday after Ash Wednesday, is in the church of St. George in Velabro (the veil of gold).
Deus, qui culpa offenderis, pœnitentia placaris; preces populi tui supplicantis propitius respice: et flagella tuæ iracundiæ, quæ pro peccatis nostris meremur, averte. Per Christum Dominum nostrum. Amen.
O God, who by sin art offended, and by penance pacified, mercifully regard the prayers of thy suppliant people: and turn away the scourges of thy wrath, which we deserve for our sins. Through Christ our Lord. Amen.
Lectio Isaiæ Prophetæ.
In diebus illis, ægrotavit Ezechias usque ad mortem: et introivit ad eum Isaias filius Araos propheta, et dixit ei: Hæc dicit Dominus: Dispone domui tuæ, quia morieris tu, et non vives. Et convertit Ezechias faciem suam ad parietem, et oravit ad Dominum, et dixit: Obsecro, Domine, memento, quæso, quomodo ambulaverim coram te in veritate, et in corde perfecto, et quod bonum est in oculis tuis fecerim. Et flevit Ezechias fletu magno. Et factum est verbum Domini ad Isaiam dicens: Vade, et dic Ezechiæ: Hæc dicit Dominus Deus David patris tui: Audivi orationem tuam, et vidi lacrymas tuas: ecce ego adjiciam super dies tuos quindecim annos: et de manu regis Assyriorum eruam te, et civitatem istam, et protegam eam, ait Dominus omnipotens.
Lesson from Isaias the Prophet.
In those days, Ezechias was sick even to death, and Isaias the son of Amos the prophet came unto him, and said to him: Thus saith the Lord: Take order with thy house, for thou shalt die, and not live. And Ezechias turned his face towards the wall, and prayed to the Lord, and said: I beseech thee, O Lord, remember how I have walked before thee in truth, and with a perfect heart, and have done that which is good in thy sight. And Ezechias wept with great weeping. And the word of the Lord came to Isaias, saying: Go and say to Ezechias: Thus saith the Lord the God of David thy father: I have heard thy prayer, and I have seen thy tears: behold I will add to thy days fifteen years: and I will deliver thee and this city out of the hands of the king of the Assyrians, and I will protect it, saith the Lord almighty.
Yesterday, the Church spoke to us upon the certainty of death. Die we must: we have not only God’s infallible word for it, but no reasonable man could ever entertain the thought that he was to be an exception to the rule. But if the fact of our death be certain, the day on which we are to die is also fixed. God, in His wisdom, has concealed the day from us; it becomes our duty not to be taken by surprise. This very night, it might be said to us, as it was to Ezechias: Take order with thy house, for thou shalt die. We ought to spend each day, as though it were to be our last. Were God even to grant us, as He did to the holy king of Juda, a prolongation of life, we must come, sooner or later, to that last hour, beyond which there is no time, and eternity begins. The Church’s intention in thus reminding us of our mortality, is to put us on our guard against the allurements of this short life, and urge us to earnestness in the great work of regeneration, for which she has been preparing us during these last three weeks. How many there are of those who yesterday received the ashes, who will never see the joys of Easter, at least in this world! To them, the ceremony has been a prediction of what is to happen to them, perhaps before the month is out. And yet the very same words that were pronounced over them, were said to us. May not we ourselves be of the number of those who are thus soon to be victims of death? In this uncertainty, let us gratefully accept the warning, which our Jesus came down from heaven to give us: ‘Do penance; for the kingdom of God is at hand.’
Sequentia sancti Evangelii secundum Matthæum.
In illo tempore: Cum introisset Jesus Capharnaum, accessit ad eum centurio, rogans eum et dicens: Domine, puer meus jacet in domo paralyticus, et male torquetur. Et ait illi Jesus: Ego veniam, et curabo eum. Et respondens centuno, ait: Domine, non sum dignus ut intres sub tectum meum; sed tantum dic verbo, et sanabitur puer meus. Nam et ego homo sum sub potestate constitutus, habens sub mo milites, et dico huic: Vado, et vadit; et alii: Veni, et venit; et servo meo: Fac hoc, et facit. Audiens autcm Jesus miratus est, et sequentibus se dixit: Amen dico vobis, non inveni tantam fidem in Israel: Dico autem vobis, quod multi ab oriente et occidente venient, et recumbent cum Abraham, et Isaac, et Jacob in regno cœlorum; filii autem regni ejicientur in tenebras exteriores: ibi erit fletus et stridor dentium. Et dixit Jesus centurioni: Vade, et sicut credidisti, fiat tibi. Et sanatus est puer in illa hora.
Sequel of the holy Gospel according to Matthew.
At that time: When Jesus had entered into Capharnaum, there came to him a centurion, beseeching him, and saying: Lord, my servant lieth at home sick of the palsy, and is grievously tormented. And Jesus saith to him: I will come and heal him. And the centurion making answer said: Lord, I am not worthy that thou shouldst enter under my roof; but only say the word, and my servant shall be healed. For I also am a man under authority, having under me soldiers; and I say to this, Go, and he goeth; and to another, Come, and he cometh; and to my servant, Do this, and he doth it. And Jesus hearing this, marvelled, and said to them that followed him: Amen, I say to you, I have not found so great faith in Israel. And I say to you, that many shall come from the east and the west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven; but the children of the kingdom shall be cast out into exterior darkness: there shall be weeping and gnashing of teeth. And Jesus said to the centurion; Go, and as thou hast believed, so be it done to thee. And the servant was healed at the same hour.
The sacred Scriptures, the fathers, and theologians, tell us that there are three eminent good works which are, at the same time, works of penance: prayer, fasting, and almsdeeds. In the lessons she gives us on these three days, which form as it were the threshold of Lent, the Church instructs us upon these works. To-day it is prayer she recommends to us. Look at this centurion, who comes to our Saviour, beseeching Him to heal his servant. His prayer is humble; in all the sincerity of his heart, he deems himself unworthy to receive Jesus under his roof. His prayer is full of faith; he doubts not for an instant that Jesus is able to grant him what he asks. And with what ardour he prays! The faith of this Gentile is greater than that of the children of Israel, and elicits praise from the Son of God. Such ought to be our prayer, when we solicit the cure of our souls. Let us acknowledge that we are not worthy to speak to God, and yet, let us have an unshaken confidence in the power and goodness of Him, who only commands us to pray that He may pour out His mercies upon us. The season we are now in is one of prayer; the Church redoubles her supplications; it is for us that she makes them; we must take our share in them. Let us, during this season of grace, cast off that languor which fastens on the soul at other times; let us remember that it is prayer which repairs the faults we have already committed, and preserves us from sin for the future.
Humiliate capita vestra Deo. Parce Domine, parce populo tuo, ut dignis flagellationibus castigatus, in tua miseratione respiret. Per Christum Dominum nostrum. Amen.
Bow down your heads to God. Spare, O Lord, spare thy people; that having been justly chastised, they may find comfort in thy mercy. Through Christ our Lord. Amen,
 St. Matt. iv. 17.