Theophylact of Bulgaria
But not only those who are gifted with the grace of teachers, but private individuals also He requires to become like salt, useful to those around them. But if he who is to be useful to others becomes reprobate, he cannot be profited, as it follows, But if the salt has lost his savour, where-with shall it be seasoned?
But because His discourse was in parables and dark sayings, our Lord, in order to rouse His hearers that they might not receive indifferently what was said of the salt, adds, He that hath ears to hear, let him hear, that is, as he has wisdom let him understand. For we must take the ears here as the perceptive power of the mind and capacity of understanding.