Those who do not learn from history are bound to repeat it.
This is the secret of the political history of modern India. Weakened by division, it succumbed to invaders; impoverished by invaders, it lost all power of resistance, and took refuge in supernatural consolations; it argued that both mastery and slavery were superficial delusions, and concluded that freedom of the body or the nation was hardly worth defending in so brief a life. The bitter lesson that may be drawn from this tragedy is that eternal vigilance is the price of civilization. A nation must love peace, but keep its powder dry.
This is an extract from: The Moslem Conquest of India, Volume 1, Chapter 16
The Story of Civilization Our oriental Heritage by Will & Ariel Durant: