Leaven And Bread

Sciens autem Jesus, dixit eis: Quid cogitatis inter vos, modicae fidei, quia panes non habetis? Nondum intelligitis, neque recordamini quinque panum, et quinque millium hominum, et quot cophinos sumpsistis? Neque septem panum, quatuor millium hominum, et quot sportas sumpsistis? Quare non intelligitis, quia non de pane dixi vobis: Cavete a fermento Pharisaeorum, et Sadducaeorum. Tunc intellexerunt, quia non dixerit, cavendum a fermento panum, sed a doctrina Pharisaeorum et Sadducaeorum. Per occasionem praecepti quo Salvator jusserat dicens: Cavete a fermento Pharisaeorum et fermento Herodis. docet eos quid significent quinque panes et septem, sive pisciculi, aut quinque milia hominum et quatuor millia, quae pasta sunt in eremo; quod licet signorum magnitudo perspicua sit, tamen et aliud in spirituali intelligentia demonstretur. Si enim fermentum Pharisaeorum et Sadducaeorum non corporalem panem, sed traditiones perversas, et haeretica significat dogmata; quare et cibi, quibus nutritus est populus Dei, non veram doctrinam integramque significent? Quaerat aliquis et dicat: Quomodo panes non habebant, qui statim impletis septem sportis, ascenderunt in naviculam, et venerunt in fines Magedan: ibique audiunt navigantes, quod cavere debeant a fermento Pharisaeorum et Sadducaeorum? Sed Scriptura testatur quod obliti sint eos secum tollere. Hoc est fermentum, de quo et Apostolus loquitur; Modicum fermentum totam massam corrumpit. Istiusmodi fermentum, quod omni ratione vitandum est, habuit Marcion, et Valentinus, et omnes haeretici. Fermentum hanc vim habet, ut si farinae mixtum fuerit, quod parvum videbatur, crescat in majus, et ad saporem suum universam conspersionem trahat: ita et doctrina haeretica, si vel modicam scintillam in tuum pectus jecerit, in brevi ingens flamma succrescit, et totam hominis possessionem ad se trahit. Denique sequitur: Tunc intellexerunt, quia non dixisset cavendum a fermento panum, sed a doctrina Pharisaeorum et Sadducaeorum. Sanctus Hieronymus, In Matthaei Evangelium Expositio, Liber Secundus, Caput XVI Source: Migne PL 25.113b-114b

Jesus was aware, and said to them, 'Why do you think among yourselves, men of little faith, that you have no bread ? Do you not understand, do you not remember the five loaves and the five thousand and how many baskets you filled? Nor the seven loaves and the four thousand and their seven loaves, and how many hampers you filled? Why do you not understand that I did not speak of bread to you when I said, 'Beware the leaven of the Pharisees and Sadducees?' Then they understood that He did not speak a warning against leavened bread but against the teaching of the Pharisees and Sadducees 1 Because of the commandment which the Savour gave saying, 'Beware the leaven of the Pharisees and the leaven of the Herodians,' He teaches them the meaning of the five loaves and the seven, and the fish, and the five thousand men and the four thousand, who were fed in the desert, the greatness of which signs it is easy to grasp, but the spiritual understanding of them may require demonstration. For if the leaven of the Pharisees and the Sadducees is not material bread, but pertains to perverse traditions and heretical teaching, why should the bread which nourished the people of God not signify true authentic teaching? Someone may ask a question about this and say, 'How did they not have bread, who just filled seven sacks and went up into the boat, and then they came to the borders of Magdalen, and there sailing heard that they should beware the leaven of the Pharisees and the Sadducees?' But Scripture bears witness that they had forgotten to bring these with them. This is the leaven, concering which the Apostle says, 'A little leaven corrupts the whole.' 2 This leaven, which in every sense is to be avoided, Marcion has, and Valentinus, and all heretics. This leaven has the power that if it is mixed with flour, then that what seemed small, grows into something great, and its aroma is diffused everywhere. Thus if even a tiny spark of hereritcal teaching is cast into the heart, then in a brief time a great flame rises up and it takes possession of the whole man. So it follows, 'Then they understood that He did not speak a warning against leavened bread but against the teaching of the Pharisees and Sadducees.' Saint Jerome, Commentary on the Gospel of Matthew, Book 2 Chap 16 1 Mt 16.8-12 2 1 Cor 5.6