We may assume that the present institutional system of the European Communities is only one stage in the long and arduous development of a European constitution. Looked at half a century hence, the trials and errors of the Coal and Steel Community; the abortive projects for a defence community and a political community; the successes and limitations of EEC and Euratom; and the vain search of the six pioneer countries for a formula for political union will appear as the first hesitant but sigruficant steps towards a complete federal system. Limited though the existing Communities are to economic and social affairs, they have now passed a point where their economies are inextricably linked, and where, although progress to more complete political unity is not automatic it is, in the long run, inevitable.