 The insistence that infinitesimals obey precisely the same algebraic rules as finite quantities forced Leibniz and the defenders of his differential calculus into treating infinitesimals, in the presence of finite quantities, as if they were zeros, so that, for example, \(x + \Dx\) is treated as if it were the same as \(x\). This was justified on the grounds that differentials are to be taken as variable, not fixed quantities, decreasing continually until reaching zero. Considered only in the “moment of their evanescence”, they were accordingly neither something nor absolute zeros.