The final trigger was seeing the Fels Naptha post at An Affordable Wardrobe. Apparently it is a stain remover to rival even my current favorite, Spray and Wash Stain Stick. I should have enough of the soap bar left after making my detergent to experiment on stains!
By the way, the saying in the title is said by some to have come from ancient Hebrew writings. However, its first appearance in English - though in slightly altered form - seems to be in the writings of Francis Bacon. In his 'Advancement of Learning' (1605) he wrote: 'Cleanness of body was ever deemed to proceed from a due reverence to God.' About two centuries later John Wesley in one of his sermons (1791) indicated that the proverb was already well known in the form we use today. Wrote Wesley: 'Slovenliness is no part of religion.'Cleanliness is indeed next to Godliness.' From "Morris Dictionary of Word and Phrase Origins" by William and Mary Morris (HarperCollins, New York, 1977, 1988).