John Lightfoot on Matthew 13:2

[So that he sat, and the whole multitude stood.] So was the manner of the nation, that the masters when they read their lectures sat, and the scholars stood: which honorary custom continued to the death of Gamaliel the Elder; and then so far ceased, that the scholars sat when their masters sat. Hence is that passage: "From that time that old Rabban Gamaliel died, the honour of the law perished, and purity and Pharisaism died." Where the Gloss, from Megillah, writes us; "Before his death health was in the world, and they learned the law standing; but when he was dead sickness came down into the world, and they were compelled to learn the law sitting."