January 25 is the Feast of the Conversion of Saint Paul. For more on this painting see the Khan Academy video
for more on this feast see: American Catholic Saint of the Day: http://www.americancatholic.org/Features/Saints/saint.aspx?id=1271
Source of image: Wikimedia Commons http://en.wikipedia.org/wiki/File:Conversion_on_the_Way_to_Damascus-Caravaggio_(c.1600-1).jpg
See also: https://carfleo.com/2013/04/14/the-conversion-of-st-paul/