The account in these verses is also recorded in Mark 8:13-21.
And when his disciples were come to the other side - That is, to the other side of the Sea of Galilee.
Mark says that he entered into a ship again, and departed to the other side. The conversation with the Pharisees and Sadducees had been on the western side of the Sea of Galilee. See the notes at Matthew 15:39. They crossed from that side again to the east.
Had forgotten to take bread - That is, had forgotten to lay in a sufficient supply. They had, it seems, not more than one loaf, Mark 8:14.
Take heed ... - That is, be cautious, be on your guard.
The leaven of the Pharisees and Sadducees - Leaven is used in making bread.
It passes secretly, silently, but certainly through the mass of dough. See the notes at Matthew 13:33. “None can see its progress.” So it was with the doctrines of the Pharisees. They were insinuating, artful, plausible. They concealed the real tendency of their doctrines; they instilled them secretly into the mind, until they pervaded all the faculties like leaven.
They reasoned ... - The disciples did not understand him as referring to the doctrine of the Pharisees and Sadducees, because the word “leaven” was not often used among the Jews to denote doctrines, no other instance of this use of the word occurring in the Scriptures. Besides, the Jews had many particular rules about the leaven (yeast) which might be used in making bread. Many held that it was not lawful to eat bread made by the Gentiles; and the disciples, perhaps, supposed that he was cautioning them not to procure a supply from the Pharisees and Sadducees.
O ye of little faith! - Jesus, in reply, said that they should not be so anxious about the supply of their temporal wants. They should not have supposed, after the miracles that he had performed in feeding so many, that he would caution them to be anxious about procuring bread for their necessities. It was improper, then, for them to reason about a thing like that, but they should have supposed that he referred to something more important. The miracles had been full proof that he could supply all their wants without such anxiety.
Then understood they ... - After this explanation they immediately saw that he referred to the doctrines of the Pharisees and Sadducees.
Erroneous doctrines are like leaven in the following respects:
- They are at first slight and unimportant in appearance, just as leaven is small in quantity as compared with the mass that is to be leavened.
- They are insinuated into the soul unawares and silently, and are difficult of detection.
- They act gradually.
- They act most certainly.
- They will pervade all the soul, and bring all the faculties under their control.