 The alliance between unity and empiricism, or physicalism, is thrown into further relief by contrast with the post-Diltheyan German sociology of Windelband, Rickert, Sombart and especially Weber. They distinguished between the natural and the social sciences and, as distinctive feature of the latter, in Weber’s sociology there appear non-scientific, non-behavioristic entities and activities such as the spirit of the age (Zeitgeist), and empathy or understanding, poetic activity that grounds what he calls ‘Verstehende sociology’ (ibid., 353). Neurath’s was willing to accept the use of such concepts provided they could be given a physicalistic meaning. 