The works of St. Cyril include a sermon on The Pool of Bethsada, a Letter to the Emperor Constantius, three small fragments and the famous Catecheses. The Catecheses contains numerous catechetical lectures, which are among the most precious remains of Christian antiquity. They include an introductory address, eighteen instructions delivered in Lent and five in Easter to those preparing for Baptism. It is in this work that St. Cyril alludes to three comings of Christ:
We do not preach only one coming of Christ, but a second as well, much more glorious than the first. The first coming was marked by patience; the second will bring the crown of a divine kingdom. In general, what relates to our Lord Jesus Christ has two aspects. There is a birth from God before the ages, and a birth from a virgin at the fullness of time. There is a hidden coming [not physically visible like the Second Coming, but in the soul], like that of rain [symbolic of grace] on fleece, and a coming before all eyes [every soul will know the true God, the Gospel preached to all creatures – Matthew 24:14], still in the future … he will come again in glory to judge the living and the dead, and his kingdom will have no end. Our Lord Jesus Christ will therefore come from heaven. He will come at the end of the world, in glory, at the last day. For there will be an end to this world, and the created world will be made new.
The Church Father and Doctor St. Cyril provides us with the expression, “the hidden coming,” that would be interpreted in the middle ages as the period that spans “from the first coming of Christ to the end of the world.” Cyril’s “hidden coming” would later be interpreted only as the intermediary time of the institutional Church, and is rediscovered in the writings of the Church Doctor St. Bernard of Clairvaux. (read St. Bernard’s version here)
Source: The Splendor of Creation by Rev. Joseph Iannuzzi