Scholarly Reflections
Daniélou, Jean, S.J. "Chapter Nineteen: Pentecost." The Bible and the Liturgy." Notre Dame, IN: University of Notre Dame Press, 1956, pp. 319-332.
Rather early in Christian thought the feast of Pentecost, at the end of the seven weeks of the Paschal season, was considered an integral part of the entire package. Theologically the incarnation, passion, resurrection, ascension, and the coming of the Holy Spirit belong together. Daniélou observes that the chronology, rather than the theology, took over in the fourth century, dividing the celebration into distinct portions (Daniélou 1956, 319). While originally Pentecost was seen as the period of seven weeks following Easter, it later began to be observed starting on the last day of the period (Daniélou 1956, 320). Philo's observation was that the period of Pentecost (meaning fifty) began the day after Passover and concluded fifty days later. The feast was seen by Philo as one of thanksgiving and complete dependence on God who provides all we need (Daniélou 1956, 322).
Though there is evidence of a recognition of the Jewish feasts by Christians at an early time, the specific Christian liturgical interpretation of the Feast of Weeks is not strongly developed until Cyril of Jerusalem (Daniélou 1956, 322). He considered the feast as a culmination of the seven week period. The Paschal feast shows Christ in the lamb. The Pentecost feast shows him in the offering of first fruits (Daniélou 1956, 324).
Daniélou observes that early Christians were quick to note the symbolic significance of a week of weeks, 49 days, plus one. They tied it quickly to the Old Testament pattern of remission of debts and manumission of slaves every fiftieth year (Daniélou 1956, 324). From this concept, Clement of Alexandria and then Origen understood the number fifty to be symbolic of forgiveness (Daniélou 1956, 325). While Jewish authors took the one day added to the seven weeks as a symbol of the unity of God, Christians tended to view it in terms of an eighth day, the day of resurrection. This was the case as early as Basil and Athanasius (Daniélou 1956, 328).
Again, Daniélou recalls that the focus of Pentecost shifted in the fourth century to Pentecost Sunday, rather than the seven weeks preceding it (Daniélou 1956, 320). In the thought of Gregory Nazienzen it was the fiftieth day which was the special marker of hope, due to the coming of the Holy Spirit. The celebration would take place particularly at the third hour of the morning, remembering the time when the Holy Spirit came. This observance led to a commemoration of Moses' reception of the Law on Mount Sinai (Daniélou 1956, 331).