Sulphur is a Substance that is called matches and has four kinds: white, yellow, red and black. The red Sulphur or Philosopher’s stone is very rare; so in Persian literature and prose beside its true meaning, is used as a metaphor for every rare and valuable thing.
Although such learned men in every century were rare and precious but these days they become philosopher's stone (Mersad olEbad. p. 543) Said is one of four elements. The black soil has a metaphor meaning, every - valuable thing.
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