Because it enters not into his heart, but into the belly, and goes out into the drain, purging all foods?
All Commentaries on Mark 7:19 Go To Mark 7
Cornelius a Lapide
AD 1637
Because it entereth not into his heart, i.e, into his soul, and cannot therefore defile it. But goeth into the belly, where the purer portion of the food, being separated, proceeds to the liver and heart; but that which is impure and feculent into the draught, by its going forth, purging, i.e, leaving pure all meats. For in that it, the impure, goeth away, it cleanses and purifies the remainder of the food.