Purity concerns whether an item is legally free from impurity; permissibility of use concerns whether it may legitimately be utilized. These may coincide but are not identical rulings.
The sanctity of human skin illustrates the distinction. Conversely, an otherwise permitted hide purified by tanning may be used as clothing or a waterskin, absent a separate prohibition.
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Tanning, Purity of Hides and Parts of Carrion
Purity concerns whether an item is legally free from impurity; permissibility of use concerns whether it may legitimately be utilized. These may coincide but are not identical rulings.
The sanctity of human skin illustrates the distinction. Conversely, an otherwise permitted hide purified by tanning may be used as clothing or a waterskin, absent a separate prohibition.