Spoilt salt

Today there are no images. In addition, I do not quite understand what is means and maybe therefore I feel I need to document it. My Persian taxi driver today was quite philosophical and talked a lot about religion and confessions when he drove me to my home from the airport. I did not quite understand where he was going and what his point was. But I played along – also not to appear impolite. And then he made the quite puzzling remark that “people often use salt to conserve things but how do they know whether the salt is not spoilt itself”?

As I said, I have no real idea what he meant but the remark was following me for the rest of the day.