By St. Silouan the Athonite
As the Gospel tells us, after the Lord's Ascension the Apostles returned (to Jerusalem) "with great joy".
The Lord knows what joy He gave them: and their souls experienced this joy.
That they had known the true Lord Jesus Christ was their first joy.
Their second joy - that they loved Him.
Their third joy - that they had known life eternal in heaven.
And their fourth joy - that they desired salvation for the world, as for themselves.
And later on they rejoiced because they came to know the Holy Spirit, and witnessed the workings of the Holy Spirit in themselves.
From Saint Silouan: The Athonite, by Archimandrite Sofroniĭ, ch. 13.