In the various states of society, armies are recruited from very different motives. Barbarians are urged by the love of war; the citizens of a free republic may be prompted by a principle of duty; the subjects, or at least the nobles, of a monarchy, are animated by a sentiment of honor; but the timid and luxurious inhabitants of a declining empire must be allured into the service by the hopes of profit, or compelled by the dread of punishment.

The History of the Decline and Fall of the Roman Empire. The 2. Ed. - London, W. Strahan 1776-1788 (ed. 1781)