A lifelong concern was to establish a proper theoretical and methodological foundation for the "human sciences" (e.g. history, law, literary criticism), distinct from, but equally "scientific" as, the "natural sciences" (e.g. physics, chemistry). He suggested that all human experience divides naturally into two parts: that of the surrounding natural world, in which "objective necessity" rules, and that of inner experience, characterized by "sovereignty of the will, responsibility for actions, a capacity to subject everything to thinking and to resist everything within the fortress of freedom of his/her own person".