Symbolism in The Crucible

There is very little symbolism in this novel outside of the Witch Trials and McCarthyism. If you want to go for a real stretch you could use religious extremism and how religious law dicated extreme punishments. The last thing I can think of that is a symbol rather than a theme would be the title itself. A "crucible" is a heat resistant container that's used to test the purity of certain substances with extremely high temperatures, and as the title states, this is exactly what was happening. Everyone in Salem was being judged and tested for purity.