Analysis of information sources in references of the Wikipedia article "Catacomb of Callixtus" in English language version.
another trait of symbolism which was associated with the Good Shepherd in its earliest representations. I refer to the milk with which the shepherd nourishes his sheep. This was represented by the jug or pail which he carries sometimes at his side...the Acts of S. Perpetua, which was written in the early years of the third century...describes a vision of the saint in these words: "I mounted and beheld a garden of vast extent, and in the midst of this garden a man seated, having white hair and the dress of a shepherd, milking sheep : and standing round about him thousands of men clothed in white. And he raised his head and looked at me, and said to me: Thou art welcome, my daughter. And he called me and he gave me some of the warm milk which he had just drawn, and I received it with folded hands and I ate it : and all about me said, Amen. And at the sound of the voice I awaked, with an indescribable taste of sweet in my mouth." From this it is evident that the jug of milk carried by the Good Shepherd is a mystic symbol of the Eucharist.