(1) Saint "Justin himself [c. 150 A.D.] seems to be aware only of the Sunday celebration, but Tertullian [c. 200 A.D.] adds the fast days on Wednesday and Friday and the anniversaries of the martyrs ... . As Tertullian calls the whole paschal season (until Pentcost) 'one long feast,' we may conclude with some justice that during this period the faithful not only communicated daily, but were also present at the Eucharistic Liturgy."
(2) "St Cyril of Jerusalem (d. 386) describes the liturgy of the Mass of his day as follows ... 'After the spritual Sacrifice, the unbloody service is completed; we pray to God, over this sacrifice of propitiation for the universal peace of the churches, for the proper guidance of the world, for the emperor, soldiers and companions, for the infirm and the sick, for those stricken with trouble, and in general for all in need of help we pray and offer up this sacrifice. We then commemorate the patriarchs, prophets, apostles, martyrs, that God may, at their prayers and intercessions graciously accept our supplication. We afterwards pray for the dead ... since we believe that it will be of the greatest advantage, if we in the sight of the holy and most awesome Victim discharge our prayers for them. The Christ, who was slain for our sins, we sacrifice to propitiate the merciful God for those who are gone before and for ourselves.'
"This beautiful passage, which reads like a modern prayer-book, is of interest in more than one connection. It proves in the first place that Christian antiquity recognized the offering up of the Mass for the deceased, exactly as the Church today recognizes requiem Masses -- a fact which is confirmed by other independent witnesses, e.g. Tertullian ..., Cyprian ..., and Augustine .... In the second place, it informs us that our so-called Masses of the Saints also had their prototype among the primitive Christians, and for this view we likewise find other testimonies -- e.g. Tertullian ... and Cyprian ... By a Saint's Mass is meant, not the offering up of the Sacrifice of the Mass to a saint, which would be impossible without most shameful idolatry, but a sacrifice, which, while offered to God alone, on the one hand thanks Him for the triumphal coronation of the saints, and on the other aims at procuring for us the saint's efficacious intercession with God."
(3) "Prototypes and starting-points for the oldest ecclesiastical feasts are the Jewish solemnities of Easter [i.e., Passover] and Pentecost. Together with the weekly Lord's Day, they remained the only universal Christian feasts down to the third century ([according to] Tertullian [and] ... Origen ...). Two feasts of Our Lord (Epiphany, Christmas) were added in the fourth century; then came the feasts of the Apostles and martyrs, in particular provinces; later on also those of some confessors (St. Martin, St. Gregory); in the sixth and seventh centuries feasts of the Blessed Virgin were added. ... In the course of centuries the ecclesiastical calendar expanded considerably, because in earlier ages every bishop had a right to establish new feasts. Later on a reduction of feasts took place ..."