Those 'on the rock' are people who on hearing the word welcome it with enthusiasm, but they have no root; they believe for a while and fall away in the hour of trial.
for Herod stood in awe of John, knowing he was a just and holy man; so he protected John — he was greatly exercised when he listened to him, still he was glad to listen to him.
indeed Simon himself believed, and after his baptism kept close to Philip, utterly astonished to see the signs and striking miracles which were taking place.