In this paper I argue that the almost forgotten early dissertation of the phenomenologist Hans Reiner Freiheit, Wollen und Aktivität. Phänomenologische Untersuchungen in Richtung auf das Problem der Willensfreiheit engages with what I call the unity problem of activity. This problem concerns the question whether there is a structure in virtue of which all instances of human activity—and not only “full-blown” intentional actions—can be unified. After a brief systematic elucidation of this problem, which is closely related to the contemporary “problem (...) of action,” I elaborate and critically discuss two relevant threads running through Reiner’s work. The first view concerns the alleged motivational asymmetry between activity and passivity according to which it is essential only for active experiences to be motivated by an underlying passivity. The second view focuses on Reiner’s phenomenology of the will, especially on his notions of “ego-centrality” and “inner will” the latter being introduced in analogy to Brentano’s notion of “inner consciousness.” These two notions are supposed to unify all manifestations of the human will, including “full-blown” intentional actions and non-intentional doings such as laughter. Reiner’s extension of will-based actions to non-intentional activity is one of the most remarkable aspects of his early work. Finally, I show that Reiner ultimately answers the unity problem in the negative because he ends up with the view that besides will-based agency he also acknowledges so-called “motor activity” which is not intrinsically related to the will. I close with a couple of tentative proposals how volitional and motor actions might be unified nonetheless. (shrink)