Pseudo-Jerome
Catena Aurea · Markusevangelium 4
And he said, Whereunto shall we liken the kingdom of God? or with what comparison shall we compare it? It is like a grain of mustard seed, which, when it is sown in the earth, is less than all the seeds that be in the earth: But when it is sown, it groweth up, and becometh greater than all herbs, and shooteth out great branches; so that the fowls of the air may lodge under the shadow of it. And with many such parables spake he the word unto them, as they were able to hear it. But without a parable spake he not unto them: and when they were alone, he expounded all things to his disciples.
Or else, that seed is very small in fear, but great when it has grown into charity, which is greater than all herbs; for God is love, (1 John 4:16) whilst all flesh is grass. (Isa. 40:6 But the boughs which it puts forth are those of mercy and compassion, since under its shade the poor of Christ, who are meant by the living creatures of the heavens, delight to dwell.