By ELIPHAS LEVI - SUPERSTITION, from the Latin word "superstes," surviving, is the sign which survives the idea which it represents; it is the form preferred to the thing, the rite without reason, faith become insensate through isolating itself. It is in consequence the corpse of religion, the death of life, stupefaction substituted for inspiration.
Fanaticism is superstition become passionate, its name comes from the word "fanum," which signifies "temple," it is the temple put in place of God, it is the human and temporal interest of the priest substituted for the honour of priesthood, the wretched passion of the man exploiting the faith of the believer.
In the fable of the ass loaded with relics, La Fontaine tells us that the animal thought that he was being adored; he did not tell us that certain people indeed thought that they were adoring the animal. These people were the superstitious. If any one had laughed at their stupidity, he would very likely have been assassinated, for from superstition to fanaticism is only one step.
Superstition is religion interpreted by stupidity; fanaticism is religion serving as a pretext to fury. Those who intentionally and maliciously confound religion itself with superstition and fanaticism, borrow from stupidity its blind prejudices, and would borrow perhaps in the same way from fanaticism its injustices and angers (THE KEY OF THE MYSTERIES p.90).