"In the year 590, when St. Gregory the Great was elected to the chair of St. Peter, ambassadors were sent from the Emperor Justinian in the East to congratulate His Holiness and tender the usual spiritual allegiance to the Vicar of Christ. When they were leaving Rome, they requested the Holy Father to give them some relic to take back to their own country. St. Gregory led them to the Coliseum. Taking up some of the clay of the arena, he folded it up in a napkin, and handed it to the ambassadors. They seemed not to appreciate the gift, and respectfully remonstrated. The holy Pope, raising his eyes and his heart towards heaven, with love and kindness beaming in his countenance, said to them, 'You know not what you have,' and taking the napkin in his hand, unfolded it, and showed it to them, stained with blood - the blood of the martyrs who suffered in the Coliseum!"
-The Martyrs of the Coliseum by Fr. A. O'Reilly of Toronto, Canada.