“A man in debt is so far a slave.”

IV, 3
Variant translation: The good man, though a slave, is free; the wicked, though he reigns, is a slave, and not the slave of a single man, but — what is worse — the slave of as many masters as he has vices.
The City of God (early 400s)
Context: The dominion of bad men is hurtful chiefly to themselves who rule, for they destroy their own souls by greater license in wickedness; while those who are put under them in service are not hurt except by their own iniquity. For to the just all the evils imposed on them by unjust rulers are not the punishment of crime, but the test of virtue. Therefore the good man, although he is a slave, is free; but the bad man, even if he reigns, is a slave, and that not of one man, but, what is far more grievous, of as many masters as he has vices; of which vices when the divine Scripture treats, it says, “For of whom any man is overcome, to the same he is also the bond-slave.”

Maxim 14
Sentences
Variant: "Debt is the slavery of the free."

Source: Books, America: Imagine a World without Her (2014), Ch. 8

2010s, 2016, July, This Week Interview (July 30, 2016)

As quoted in "The Best Of The Rest: 20 More Quotes About Liberals" at Right Wing News (24 November 2010) http://rightwingnews.com/quotes/the-best-of-the-rest-20-more-quotes-about-liberals/

Tanto è miser l'uom quant' ei si riputa.
Ecloga Octava; reported in Hoyt's New Cyclopedia Of Practical Quotations (1922), "Mind".

Source: 1840s, Narrative of the Life of Frederick Douglass, An American Slave (1845), Ch. 10

Presidential Radio Address (24 February 2001) http://www.cbsnews.com/stories/2001/02/24/national/main274334.shtml
2000s, 2001