From Wikipedia: The painting has been considerably damaged and retouched, and what
remains of Caravaggio's brushwork is the angel, who bears a resemblance
to the figure in John the Baptist at the Fountain. The illusionistic treatment of the angel, floating on his cloud and seeming to protrude outside the picture plane, is more Baroque
than is normal for Caravaggio, but the contrast between the energetic
pose of the heavenly messenger and the receptive Mary is dramatically
and psychologically effective. The loose brushwork is typical of
Caravaggio's later period.
We rightly admire Muslim neighbors and co-workers who put everything on hold five times a day in answer to the "call to prayer." But Christians have a call to prayer, too! It is the Angelus. Morning, noon and evening we are invited to pause and reaffirm our faith in the Incarnation: The Word was made flesh and dwelt among us (Jn. 1:14), because "God so loved the world that he sent his only Son" (Jn. 3:16).