That public virtue which among the ancients was denominated patriotism, is derived from a strong sense of our own interest in the preservation and prosperity of the free government of which we are members. Such a sentiment, which had rendered the legions of the republic almost invincible, could make but a very feeble impression on the mercenary servants of a despotic prince; and it became necessary to supply that defect by other motives, of a different, but not less forcible nature; honour and religion.
Edward Gibbon (2009). “The Decline and Fall of the Roman Empire (Edited and Abridged): Abridged Edition”, p.15, Modern Library