Part 9 · Chapter 74

It will also be clarified below that these Gevurot [judgments] are two kinds of blood, each comprising five. Five of them are called five kinds of impure blood, and the other five are called pure blood. Therefore the Gevurot called wine — which at times become blood, and the outer ones suckle from it — require guarding, a seal within a seal. But the Hasadim [mercies], called water, the outer ones have no grasp on them; therefore they require no guarding.