The lambda-mu-calculus plays a central role in the theory of programming languages as it extends the Curry-Howard correspondence to classical logic. A major drawback is that it does not satisfy Böhm's Theorem and it lacks the corresponding notion of approximation. On the contrary, we show that Ehrhard and Regnier's Taylor expansion can be easily adapted, thus providing a resource conscious approximation theory. This produces a sensible lambda-mu-theory with which we prove some advanced properties of the lambda-mu-calculus, such as Stability and Perpendicular Lines Property, from which it follows the impossibility of parallel computations.