This painting "The Pentecost" by Gaetano Gandolfi (1734-1802) is a depiction of
the descent of the Holy Ghost to the gathering of
the Apostles on the Jewish holiday of Pentecost,
as described in ACTS, Chapter 2

The Pentecost "When the day of Pentecost came, they were all together in one place. Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. They saw what seemed to be tongues of fire that separated and came to rest on each of them. All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them. Now there were staying in Jerusalem God-fearing Jews from every nation under heaven. When they heard this sound, a crowd came together in bewilderment, because each one heard them speaking in his own language. Utterly amazed, they asked: "Are not all these men who are speaking Galileans? Then how is it that each of us hears them in his own native language? Parthians, Medes and Elamites; residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya near Cyrene; visitors from Rome (both Jews and converts to Judaism); Cretes and Arabs--we hear them declaring the wonders of God in our own tongues!" Amazed and perplexed, they asked one another, "What does this mean?" ACTS 2:1-12