Foreign And Civil Wars

William Edward Lecky, History of European Morals From Augustus to Charlemagne, vol. I., (New York: 3rd edt., 1897), ch. 2, The Pagan Empire, p. 232:

Foreign wars, which develop with great intensity distinctive national types, and divert the public mind from internal changes, are usually favourable to the conservative spirit; but civil wars are essentially revolutionary, for they overwhelm all class barriers and throw open the highest prizes to energy and genius.