Nicene and Post-Nicene Fathers: Series I/Volume IV/Donatist Controversy/On Baptism/Book VII/Chapter 31
Chapter 31.—60. Tenax of Horrea Celiæ[1] said: "There is one baptism, but of the Church; and where the Church is not, there baptism also cannot be."[2]
61. To him we answer: How then comes it that it may be where the rock is not, but only sand; seeing that the Church is on the rock, and not on sand?