This concept of power keeps referring its users to a domain of apparent antinomies, which from a formal theoretical perspective are in turn construed as unities in opposition to further terms. Three such sequences are 'power to' and 'power over', power as capacity and as right, and juridical conceptions of sovereignty and 'economic' conceptions of government. This movement of opposition, unity and renewed opposition is however the signature of the concept of power, which, instead of being transcended or neutralised, must be kept in play in its analysis. As a consequence of the view that there is no essence of power, the paper further argues for a substantive rather than formal approach to power in which the analysis of power proceeds by paradigmatic cases, analogies and exemplars. The work of Ernst H. Kantorowicz, Michel Foucault, Max Weber and Giorgio Agamben helps to elucidate this approach.