Castile is the purest, simplest soap possible - it contains saponified organic olive oil and filtered water only.This soap is ideal for those with sensitive skin or eczema as it has no scent or other potentially irritating ingredients and it does not dry the skin.
In Northern Europe, soaps were traditionally made with rendered animal fats like beef tallow and lard (and many still are). - these went rancid rapidly & stunk to high heaven. Olive oil soaps were made in Southern Spain from the 8th century & were highly sought after (& expensive) because they were milder on the skin & didn’t smell bad.
Pure Olive oil soaps like this one don't produce much of a lather but this isn't a defect. So don't worry if your soap won't seem to 'get going' - it will still clean as well as fluffier formulas!