There is moreover a reason in the subject of His discourse why the Lord should sit in the ship, and the multitude stand on the shore. For He was about to speak in parables, and by this action signifies that they who were without the Church could have no understanding of the Divine Word.
The ship offers a type of the Church, within which the word of life is placed, and is preached to those without, and who as being barren sand cannot understand it.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).