Catena Aurea on Matthew 13:34–35: Augustine of Hippo

Or, this is said, not in Matt that He uttered nothing in plain words but that He concluded no one discourse without introducing a parable in the course of it, though the chief part of the discourse might consist of matter not figurative. And we may indeed find discourses of His parabolical throughout, but none direct throughout. And by a complete discourse, I mean, the whole of what He says on any topic that may be brought before Him by circumstances, before He leaves it, and passes to a new subject.

For sometimes one Evangelist connects what another gives as spoken at different times; the writer having in such a case followed not the order of events, but the order of connexion in his own memory. The reason why He spake in parables the Evangelist subjoins, saying, “That it might be fulfilled that was spoken by the Prophet, saying, I will open my mouth. in parables, I will utter things kept secret from the foundation of the world.” [Ps 78:2]