The Gospel of Thomas is a recently discovered Gospel that was in wide use among early Christian groups, but which never made it into the official canon of the Bible. One verse reads: "His disciples asked, 'When will you become revealed to us and when shall we see you?' Jesus answered, 'When you disrobe without being ashamed and take up your garments and place them under your feet like little children and tread on them, then will you see the son of the Living One, and you will not be afraid.' " Nudity in this case appears to be refer to achieving a state of personal innocence.
"The Little Flowers of St. Francis", Part I, Chapter 30.