which led him to share this interpretation. Willard Swartley states that by obeying the Golden Rule one becomes the fertilizing salt of the earth. Phil Schmidt also believes that the disciples are meant to stimulate growth and positively affect the world. Schweizer notes that a common Jewish expression at the time was to call the Laws the "salt and the light" of the world, which may mean this section is an introduction to the discussion of Mosaic law that will soon commence. In the Rabbinic literature of the period salt was a metaphor for wisdom. Salt also played role in ritual purity and all sacrifices had to contain salt. John Nolland argues that the many different uses of salt show its importance in the life of the period, and it is this importance of the disciples that is being referenced. Ancient peoples sometimes put salt on the wicks of lamps to increase their brightness. Losing saltiness The issue of salt losing its flavour is somewhat problematic. Salt itself, sodium chloride (), is extremely stable and cannot lose its flavour. France notes that Jesus was giving a lesson in moral philosophy and "not teaching chemistry"; to him, whether or not the proverbial image is factually accurate is of little relevance to the actual message of this verse. Nolland considers the impossibility of what is described as deliberate, it is counter to nature that salt lose its flavour, just as it is counter to God's will that the disciples lose faith. The most common explanation for this is that what would have been called salt in that era was quite impure, containing a wide array of other compounds. Of the substances in this mix the was the most soluble in water and if exposed to moisture the would disappear leaving a white powder looking just like salt, but not having its flavour or its preservative abilities. The salt used in the area mostly came from mines around the Dead Sea and material extracted from that area demonstrates these same properties today. Gundry notes that some other explanations have been advanced. Salt was extremely valuable and unscrupulous merchants may have replaced the salt with other substances. For some purposes gypsum was added to salt, but this would erase its flavour and make it unfit for consumption. Albert Barnes, in his Notes on the Bible (1834) says: In eastern countries, however, the salt used