1 sn Salt was used as seasoning or fertilizer (BDAG 41 s.v. ἅλας a), or as a preservative. If salt ceased to be useful, it was thrown away. With this illustration Jesus warned about a disciple who ceased to follow him.
2 sn The difficulty of this saying is understanding how salt could lose its saltiness since its chemical properties cannot change. It is thus often assumed that Jesus was referring to chemically impure salt, perhaps a natural salt which, when exposed to the elements, had all the genuine salt leached out, leaving only the sediment or impurities behind. Others have suggested the background of the saying is the use of salt blocks by Arab bakers to line the floor of their ovens: Under the intense heat these blocks would eventually crystallize and undergo a change in chemical composition, finally being thrown out as unserviceable. A saying in the Talmud (b. Bekhorot 8b) attributed to R. Joshua ben Chananja (ca.