A multiple-circuit, hydraulically open brake has two single-circuit pressure generators hydraulically connected in parallel between at least one fluid container and at least two wheel brakes and a modulation unit for individual brake pressure modulation in the at least two wheel brakes. A first pressure generator is assigned to a main system which has a first energy supply and a first evaluation and control unit, and a second single-circuit pressure generator is assigned to a secondary system, which has a second energy supply which is independent of the first energy supply, and a second evaluation and control unit. The second evaluation and control unit controls the second pressure generator. Components of the modulation unit are assigned to the main system so that the modulation unit and the first pressure generator are controlled by the first evaluation and control unit and supplied with energy by the first energy supply.