The Holy Spirit is often portrayed as a descending dove because of the baptism of Christ, described in Matthew 3:17,
"And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, “This is my beloved Son, with whom I am well pleased.”"
Today we reflect upon the Third Person of the Trinity, and pray with King David the following:
"Create in me a clean heart, O God,
and renew a right spirit within me.
Cast me not away from your presence,
and take not your Holy Spirit from me.
Restore to me the joy of your salvation,
and uphold me with a willing spirit." (see Psalm 51)