Do not you yet understand, that whatever enters in at the mouth goes into the belly, and is cast out into the draught?…
The Saviour does not stop to prove that these things come out of the heart. He asserts it, and asserts it because it is self-evident. When you see a thing coming forth, you are clear it was there first. Last summa.: I noticed hornets continually flying from a number of decayed logs in my garden. I saw them constantly flying in and out, and I did not think myself at all unreasonable in concluding that there was a hornet's nest there; and so, if we see the hornets of sin flying out of a man, we suppose at once there is sin within him.
(C. H. Spurgeon.)
Parallel VersesKJV: Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught?