In this paper, we provide a novel approach to describe and analyze memristive circuits. This method is based on a Volterra series representation of the essential time functions of the circuit. This does not only provide the possibility of calculating voltages and currents over time in specific memristive networks, but describes the behavior of a general single memristor circuit, e.g. a circuit with an arbitrary linear two-port which is coupled to a memristor and a current source. We consider this approach as a first step in the direction of a comprehensive memristive network theory.