The Spirit of God descending as a dove
(pneuma qeou katabainon wsei peristeran
). It is not certain whether Matthew means that the Spirit of God took the form of a dove or came upon Jesus as a dove comes down. Either makes sense, but Luke ( Luke 3:22
) has it "in bodily form as a dove" and that is probably the idea here. The dove in Christian art has been considered the symbol of the Holy Spirit.