Notes

1: Diognetus was one of Marcus’ teachers, a painting master who proved particularly influential, seemingly to have converted Marcus to the philosophic way of life. In April 132, at the behest of Diognetus, Marcus took up the dress and habits of the philosopher. He studied while wearing a rough Greek cloak, and would sleep on the ground until his mother convinced him to sleep on a bed.  

2: Quintus Junius Rusticus was a Stoic philosopher and one of Marcus teachers, whom he treated with the utmost respect and honor.
Rusticus held the political positions of Suffect consul in 133 and Consul ordinarius in 162. He served as urban prefect of Rome between 162 and 168. In this role he is notable for presiding over the trial of the Christian theologian Justin Martyr, which ended with Justin's conviction and execution, illustrated on page 4.  

3: The Sophists were paid teachers of philosophy and rhetoric, who used specious reasoning and were skeptical of morals.
Sophistry is using fallacious arguments designed to fool.
Sophistication is having a great deal of knowledge of fashion and culture; in essence, fakery. Sophism is the modern prevailing philosophy. People today are more concerned with looks than use, the adage “form follows function” having fallen out of favor long ago.  

4: Apollonius was one of Marcus’ teachers who first introduced him to philosophy.  

5: Sextus of Chaeronea was a philosopher, a nephew or grandson of Plutarch, and one of the teachers of the emperor Marcus Aurelius.  

6: Fronto was Marcus’ teacher in Latin oratory before he discovered philosophy. Fronto hated that fact. “It is better never to have touched the teaching of philosophy… than to have tasted it superficially, with the edge of the lips, as the saying is.”  

7: Claudius Maximus was a Roman politician, a Stoic philosopher, and a teacher of Marcus Aurelius. No works by him are known to exist.  

8: Cecrops was a mythical king of Attica which derived from him its name Cecropia, having previously borne the name of Acte or Actice (from Actaeus). He was the founder and the first king of Athens itself though preceded in the region by the earth-born king Actaeus of Attica. Cecrops was a culture hero, teaching the Athenians marriage, reading and writing, and ceremonial burial.  

8: Vespasian was Roman emperor from 69 to 79. The fourth and last in the Year of the Four Emperors, he founded the Flavian dynasty that ruled the Empire for 27 years.  

9: Trajan was Roman emperor from 98 to 117. Officially declared by the Senate optimus princeps (“best ruler”), Trajan is remembered as a successful soldier-emperor who presided over the greatest military expansion in Roman history, leading the empire to attain its maximum territorial extent by the time of his death. He is also known for his philanthropic rule, overseeing extensive public building programs and implementing social welfare policies, which earned him his enduring reputation as the second of the Five Good Emperors, who presided over an era of peace and prosperity in the Mediterranean world.  

10: Heraclitus of Ephesus was an Ancient Greek, pre-Socratic, Ionian philosopher and a native of the city of Ephesus, which was then part of the Persian Empire.
His appreciation for wordplay and oracular expressions, as well as paradoxical elements in his philosophy, earned him the epithet “The Obscure” from antiquity. He wrote a single work, On Nature, only fragments of which have survived, increasing the obscurity associated with his life and philosophy. Heraclitus’s cryptic utterances have been the subject of numerous interpretations. He has been seen as a “material monist” or a process philosopher; a scientific cosmologist, a metaphysician and a religious thinker; an empiricist, a rationalist, a mystic; a conventional thinker and a revolutionary; a developer of logic—one who denied the law of non-contradiction; the first genuine philosopher and an anti-intellectual obscurantist.  

11: The writings of Crates are lost. Crates of Thebes was a Cynic philosopher who gave away his money to live a life of poverty on the streets of Athens. Respected by the people of Athens, he is remembered for being the teacher of Zeno of Citium, the founder of Stoicism. Various fragments of Crates’ teachings survive, including his description of the ideal Cynic state.
Xenocrates of Chalcedon was a Greek philosopher, mathematician, and leader of the Platonic Academy from 339 to 314 BC. His teachings followed those of Plato, which he attempted to define more closely, often with mathematical elements. He distinguished three forms of being: the sensible, the intelligible, and a third compounded of the two, to which correspond respectively, sense, intellect and opinion. He considered unity and duality to be gods which rule the universe, and the soul a self-moving number. God pervades all things, and there are demonical powers, intermediate between the divine and the mortal, which consist in conditions of the soul. He held that mathematical objects and the Platonic Ideas are identical, unlike Plato who distinguished them. In ethics, he taught that virtue produces happiness, but external goods can minister to it and enable it to effect its purpose.  

12): It was only a century ago that we discovered that the universe was thirteen or fourteen billion years old, and that the Earth itself is four billion. Before Edwin Hubble discovered that the universe was expanding, it had been assumed that it was timeless.  

13: Antoninus Pius was Marcus’ legal stepfather, although his mother and grandfather raised Marcus. Antonius was the emperor before Marcus.  

14: He didn’t want to become emperor. His biographer wrote that he was “compelled” to take imperial power. With his preference for the philosophic life, he found the imperial office unappealing. His training as a Stoic, however, had made the choice clear to him that it was his duty.  

15): Gold and silver, rather than being the “Earth’s feces”, were actually expelled from exploding stars and deposited on Earth, but there was no way anyone in antiquity could know that.  

16: Cithaeron is a mountain and mountain range about ten miles long in central Greece. The range is the physical boundary between Boeotia in the north and Attica in the south.  

17: In the original tale, a proud town mouse visits his cousin in the country. The country mouse offers the city mouse a meal of simple country cuisine, at which the visitor scoffs and invites the country mouse back to the city for a taste of the “fine life” and the two cousins dine on white bread and other fine foods. But their rich feast is interrupted by a cat which forces the rodent cousins to abandon their meal and retreat back into their mouse hole for safety. Town mouse tells country mouse that the cat killed his mother and father and that he is frequently the target of attacks. After hearing this, the country mouse decides to return home, preferring security to opulence or, as the 13th-century preacher Odo of Cheriton phrased it, “I’d rather gnaw a bean than be gnawed by continual fear”.  

18: Pythagoreanism originated in the 6th century BC, based on the teachings and beliefs held by Pythagoras and his followers, the Pythagoreans.
Pythagoras was already in ancient times well known for the mathematical achievement of the Pythagorean theorem. Pythagoras had been credited with discovering that in a right-angled triangle the square of the hypotenuse is equal to the sum of the squares of the other two sides. In ancient times Pythagoras was also noted for his discovery that music had mathematical foundations. Antique sources that credit Pythagoras as the philosopher who first discovered music intervals also credit him as the inventor of the monochord, a straight rod on which a string and a movable bridge could be used to demonstrate the relationship of musical intervals.  

19: Ephesus was an ancient Greek city on the coast of Ionia, about 1.8 miles southwest of present-day Selçuk in Izmir Province, Turkey. It was built in the 10th century BC on the site of the former Arzawan capital by Attic and Ionian Greek colonists. During the Classical Greek era it was one of the twelve cities of the Ionian League.  

20: Empedocles maintained that as the best and original state, there was a time when the pure elements and the two powers co-existed in a condition of rest and inertness in the form of a sphere. The elements existed together in their purity, without mixture and separation, and the uniting power of Love predominated in the sphere: the separating power of Strife guarded the extreme edges of the sphere. Since that time, strife gained more sway and the bond which kept the pure elementary substances together in the sphere was dissolved. The elements became the world of phenomena we see today, full of contrasts and oppositions, operated on by both Love and Strife. The sphere of Empedocles being the embodiment of pure existence is the embodiment or representative of God. Empedocles assumed a cyclical universe whereby the elements return and prepare the formation of the sphere for the next period of the universe.