A great civilization is not conquered from without until it has destroyed itself from within. The essential cause of Rome’s decline lay in her people, her morals, her class struggle, her failing trade, her bureaucratic despotism, her stifling taxes, her consuming wars. Rome was not destroyed by Christianity any more than by barbarian invasion; it was an empty shell when Christianity rose to influence and the invasion came.

— Will Durant (1885-1981) and Ariel Durant (1898-1981), American historians