9 For not without reason do many call this the resurrection of the martyrs. I do not say whether they have risen for themselves, for us certainly the martyrs have risen. You know— nay, you have yourselves seen— that many are cleansed from evil spirits, that very many also, having touched with their hands the robe of the saints, are freed from those ailments which oppressed them; you see that the miracles of old time are renewed, when through the coming of the Lord Jesus grace was more largely shed forth upon the earth, and that many bodies are healed as it were by the shadow of the holy bodies. How many napkins are passed about! How many garments, laid upon the holy relics and endowed with healing power, are claimed! All are glad to touch even the outside thread, and whosoever touches will be made whole.
Source: Letters (New Advent)