Miscellanies 6.15.119

They say that grafting is done in four ways. One is that in which the graft must be fitted between the wood and the bark; so the uneducated from the Gentiles are catechized, receiving the Word superficially. The second is when they split the wood and insert the noble shoot into it; this happens with those who have studied philosophy, for when their doctrines are cut through, the knowledge of the truth grows in them. So too with the Jews: when the old Scripture is opened up, the new and noble shoot of the olive is grafted in. The third grafting concerns wild plants and the heretics who are brought over to the truth by force; for, having shaved each piece to a wedge with a sharp pruning knife until the pith is laid bare but not wounded, they bind them to each other. The fourth way of grafting is what is called budding: an eye is removed from a noble stem, with the bark around it cut out in a circle about a palm's breadth long; then the stem to be budded is scraped out at an eye to match the cut-out piece, and so the bud is inserted, bound round with cord and plastered with clay, the eye being kept unhurt and unsoiled. This is a figure of the knower's teaching, which is able to look into things; and indeed this form is most useful with cultivated trees.