Reverence in Church: A Cautionary Tale

From Fr. Finigan's blog:

It is related of St Catherine of Siena, who was also favoured with the visible presence of her Guardian Angel, that once while praying in the church she turned her head slightly to gratify her curiosity. Her Guardian Angel gave her so severe a look for her disrespect in the presence of the Most Holy that for several days St Catherine was inconsolable and performed severe penance in atonement.