Judges 9:8

And no one has been so illiterate as to think that similar fables of Aesop, related for the same purpose, ought to be called lies. But also in the sacred writings such passages are found, as in the book of Judges the trees look for a king to rule over them and speak to the olive and the fig and the vine and the bramble. Surely, all this is invented in order that we may reach the matter intended by means of a narrative [that is] fictitious, to be sure, but bearing a true and not a false signification.

But lest I should appear to some to be sophistical, and to conjecture these things from mere probabilities, and to babble, I will bring forward to you, O virgins, from the Old Testament, written prophecy from the book of Judges, to show that I speak the truth, where the future reign of chastity was already clearly foretold.…Now it is clear that these things are not said of trees growing out of the earth. Inanimate trees cannot be assembled in council to choose a king since they are firmly fixed to the earth by deep roots. But on the whole these things are narrated concerning souls that—before the incarnation of Christ—luxuriated too deeply in transgressions, who approach God as beggars asking for mercy so that they may be governed by his pity and compassion. This mercy is what Scripture expresses by the figure of the olive, because oil is of great advantage to our bodies: it takes away our fatigue and ailments and offers light. For all lamplight increases when nourished by oil. So also God's mercies entirely dispel death, assist the human race and nourish the light of the heart. Consider the laws [which were in effect] from the first created man successively on to Christ. Weren't they imaginatively set forth in these words by the Scripture, in opposition to which the devil has deceived humanity? In it the fig tree has been associated with the command given to the man in paradise, because, when he was deceived, he covered his nakedness with the leaves of a fig tree; and the vine [has been related] to the instruction given to Noah at the time of the deluge, because he was mocked when overpowered by wine. The olive signifies the law given to Moses in the desert, because the prophetic grace, the holy oil, had failed from their inheritance when they broke the law. Lastly, the bramble aptly refers to the law that was given to the apostles for the salvation of the world: by their instruction we have been taught virginity, which is the only figure that the devil has not been able to make into a deceptive image. For this reason, also, the four Gospels have been given, because God has four times given the gospel to the human race and has instructed them by four laws, the times of which are clearly known by the diversity of the fruits. For the fig tree, on account of its sweetness and richness, represents the delights of man, which he had in paradise before the fall.…