The materialism controversy, which tore the middle 19th century intellectual German society apart, involved scientists, theologians, philosophers, teachers, and even more. Hermann Lotze, who at first was not willing to engage in this dispute, was soon appealed to as an arbiter based upon his previous epistemological writings concerning life sciences, psychology and natural science in general. Since he appeared to defend both a mechanistic point of view in natural science and spiritualism in metaphysics, representatives of both these extreme positions thought he could help backing up their own views during the controversy. Yet, as Lotze himself described it, the controversy was for him only "useless torture". This paper aims at showing that Lotze's specific role in the controversy corresponds to what we will assume to be a clear theoretical need of the time: i.e., a critical assessment of how to connect natural science with metaphysics.