Source: St. John Vianney, The Meditations of the Curé D’Ars
The image depicts a miraculous Communion received by St. Catherine of Siena. St. Catherine was going to omit receiving Communion because of her schedule and her need to rush out from Mass quickly before she had time to adequately pray with the Eucharist in her. During the Eucharist prayers, an angle brought a piece of the consecrated Host to her. St. Catherine exhibited extraordinary faith, humility and modesty before the Blessed Sacrament and was graced with this miracle.