Bede the Venerable
Catena Aurea · Lukasevangelium 17
Lk 17, Verses 5–6English original
And the apostles said unto the Lord, Increase our faith. And the Lord said, If ye had faith as a grain of mustard seed, ye might say unto this sycamine tree, Be thou plucked up by the root, and be thou planted in the sea; and it should obey you.
Or our Lord here compares perfect faith to a grain of mustard seed, because it is lowly in appearance, but fervid in heart. But mystically by the mulberry tree, (whose fruit and branches are red with a blood-red colour,) is represented the Gospel of the cross, which, through the faith of the Apostles being uprooted by the word of preaching from the Jewish nation, in which it was kept as it were in the lineal stock, was removed and planted in the sea of the Gentiles.