According to Sufi tenets the two aspects of the supreme Being are termed Zat and Sifat, the Knower and the Known. The former is Allah and the latter Mohammed. Zat being only one in its existence, cannot be called by more than one name, which is Allah; and Sifat, being manifold in four different involutions, has numerous names, the sum of them all being termed Mohammed. The ascending and descending forms of Zat and Sifat form the circle of the Absolute. These two forces are called Nuzul and Uruj, which means involution and evolution. Nuzul begins from Zat and ends in Sifat; Uruj starts from Sifat and ends in Zat, Zat being the negative and Sifat the positive force.