Mark 9:50

(v. Vict. Ant. in Cat.) Concerning which it is added: Salt is good; that is, the fire of love. But if the salt have lost his saltness, that is, is deprived of itself, and that peculiar quality, by which it is called good, where with will ye season it? For there is salt, which has saltness, that is, which has the fulness of grace; and there is salt, which has no saltness, for that which is not peaceful is salt unseasoned. (v. Vict. Ant. in Cat.) Or, according to Matthew, the disciples of Christ are the salt, which preserves the whole world, resisting the rottenness which proceeds from idolatry and sinful fornication. For it may also be meant, that each of us has salt, in as far as he contains in himself the graces of God. Wherefore also the Apostle joins together grace and salt, saying, Let your speech be always with grace, seasoned with salt. (Col. 4:6) For salt is the Lord Jesus Christ, Who was able to preserve the whole earth, and made many to be salt in the earth: and if any of these be corrupted, (for it is possible for even the good to be changed into corruption,) they are worthy to be cast out.

(De cura past. iii. c. 22) Or this is said against those whom greater knowledge, while it raises above their neighbours, cuts off from the fellowship of others; thus the more their learning increases, the more they unlearn the virtue of concord. (Ibid. ii. 4) He also who strives to speak with wisdom should be greatly afraid, lest by his eloquence the unity of his hearers be thrown into confusion, lest, while he would appear wise, he unwisely cut asunder the bonds of unity.

(ubi sup.) Or the good salt is the frequent hearing of God's word, and the seasoning the hidden parts of the heart with the salt of spiritual wisdom.

But if it be without saltness, that is, if its virtue of drying up and preserving be gone, with what shall it be salted? Or else, he who binds himself to his neighbour by the tie of love, has salt, and in this way peace with his neighbour.

Or otherwise; That salt is saltless which loves the chief place, and dares not rebuke others. Wherefore there follows, Have salt in yourselves, and have peace one with another. That is, let the love of your neighbour temper the saltness of rebuke, and the salt of justice season the love of your neighbour.