Leo the Great

To the Hebrew people, now freed from Egypt, the law was given on Mount Sinai fifty days after the immolation of the paschal lamb. Similarly, after the passion of Christ in which the true Lamb of God was killed, just fifty days after his resurrection, the Holy Spirit fell upon the apostles and the whole group of believers. Thus the earnest Christian may easily perceive that the beginnings of the Old Covenant were at the service of the beginnings of the gospel and that the same Spirit who instituted the first established the Second Covenant.