Mar 9:50 Salt [is] good: but if the salt have lost his saltiness...

Mar 9:50 Salt [is] good: but if the salt have lost his saltiness, wherewith will you season it? Have salt in yourselves, and have peace one with another.

Alternative: Salt is beautiful but if salt becomes unsalted, how do you fix it? Keep salt in yourselves and reconcile with each other.

While parts of this verse looks like Mat 5:13 in English translation, the underlying Greek is different. This change in vocabulary makes sense because in that earlier verse, Christ was making a play on the Greek phrase "fool's salt" for something that is falsely valuable.  In this verse, those plays on words are gone.

What remains is the sense of salt as a preservative and something of value as explained in that earlier post. Translated around that symbolic meaning, this verse becomes: Preservatives are wonderful, but if the preservative loses its ability to preserve, what can fix it? Preserve the preservative within yourselves and live peacefully with each other.

Putting this idea into the context of the chapter, which explores the interaction of the temporal and the spiritual world, this becomes: The world's preservatives are wonderful, but in this world, no preservative keeps forever, and how can you fix that? Preserve the spirit within yourselves and live peacefully with each other.

This verse highlight the reversal that takes place between the temporal and spiritual world.  In this temporary world, not even a preservative can be preserved. This is in stark contrast with the eternal ( see Mar 9:48) where the most temporary of life forms (worms) and natural conditions (fire) go on forever.

"Salt" is from halas (halas) ( see hals for more detail), which means "salt," "salt-rock," "brine," and is a metaphor for "sales" and "wit."

"Good" is from kalos (kalos), which means "beautiful," "good," "of fine quality," "noble," and "honorable." It is most often translated as "good" juxtaposed with "evil" in the New Testament, but the two ideas are closer to "wonderful" and "worthless," "noble" and "base."

"Has lost" is from gignomai (ginomai), which means "to become," "to come into being," "to be produced," and "to be."

"Saltiness" is from analos (analos), which means "unsalted," "without salt," and "not salted."

"Season" is from artuô (artyo), which means "arrange," "prepare," "make ready," "dress savoury (meat)," "season," "administer (property)," and "bequeath."

"Have" is from echô (echo), which means "to have," "to hold," "to possess," "to keep," "to have charge of," "to maintain," "to hold fast," "to bear," "to keep close," "to keep safe," and "to have means to do."

"Peace" is from eirêneuô (eireneuo), which means "bring peace to," "reconcile," "keep peace," and "live peaceably."

"One with another" is from allêlôn (allelon), which means "one another," "to one another," "mutually," and "reciprocally."