1. Anon. Rhetorica ad Herennium c. 80 BCE (trans. Lacius Curtius). Accessed April 20, 2021. https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Rhetorica_ad_Herennium/4B*.htm.
2. Aristotle. Metaphysics, c. 350 BCE (Perseus Project).
3. Augustine, St. On Christian Doctrine c. 425. Accessed April 20, 2021. https://www.newadvent.org/fathers/12021.htm.