(EN) Francis Fukuyama, The End of History and the Last Man, New York, Simon and Schuster, 2006, pp. xvi–xvii, ISBN 978-0743284554. URL consultato il 29 luglio 2018.
«[...] Plato in the Republic [...] noted that there were three parts to the soul, a desiring part, a reasoning part, and a part that he called thymos, or 'spiritedness.' [...] The propensity to feel self-esteem arises out of the part of the soul called thymos.»