Suetonius is most famous for his history of the Roman Empire, De Vita Caesarum, widely known in English as The Twelve Caesars. Marcus Aurelius was an Emperor himself, also known for his philosophical work, The Meditations. Juvenal and Plautus were Roman comedy authors, while Aeschylus was a Greek playwright.

Plato's works were largely written as dialogues, conversations between two different thinkers on a weighty topic. In most of the dialogues, the key figure was Plato's teacher, Socrates. Socrates is considered one of the leading progenitors of Western philosophy, largely thanks to the writings of Plato.

While all the Roman Emperors read philosophy and a few others wrote literary works, only Marcus Aurelius, emperor from 161-180 CE, actually wrote a philosophical tract, known as The Meditations. Marcus Aurelius' Meditations were a development on Stoic philosophy, and the work is really a collection of thoughts and quotations compiled while Marcus Aurelius was Emperor and leading the Roman Army on campaigns.

De Oratore was considered a model of how to conduct rhetoric and oratory, not only in the ancient world, but throughout European history into the Renaissance. Its author, Cicero, became widely beloved in the Middle Ages and beyond for his philosophical focus on the engaged moral and noble man.

The three great Greek philosophers are uniquely tied together, through a series of teacher-student relationships. Socrates, the great founder of Greek philosophy, directly taught Plato, who recorded most of Socrates' thought. Plato then taught Aristotle himself, which makes the entire chain of Greek philosophy tied to all three.

Located in his work The Republic, the allegory of the cave is one of the most famous ideas associated with the Greek philosopher Plato. Taking place in a dialogue with Socrates, the allegory describes people chained inside a cave, forced to watch only the images projected by shadows on the cave wall and assuming this is reality. Plato has Socrates assert that a philosopher's role is to bring people out of the cave and into reality by destroying what they assumed by only watching the shadows in the cave.

During the period of the Pre-Socratics (literally, the philosophers before Socrates), many Greek thinkers focused on trying to figure out the nature of the world. They wanted to figure out how one thing (like a human person or even a rock) could be made up of many parts (like the organs, tissues, or even mere molecules involved in the former). When you read the Pre-Socratics, they can seem pretty crazy, but they were on to something, so to speak. They wanted to figure out just what it means for one thing to be many and for a thing to change (but still remain this or that particular thing).

Heraclitus was well known for cryptic sayings. Indeed, he was so well known that a minor American philosopher who used to live in Washington, DC was called the "Heraclitus of the Potomac," meaning that he was as difficult to understand as was Heraclitus.

In any case, Heraclitus is well known for some form of the saying, "You cannot step into the same river twice." One of Heraclitus's insights (among many others) was that change plays an important role in everything that we experience. Thus, when you walk into a river, it has certain molecules. When you step in again, those molecules have gone by and new ones have replaced it. Of course, if we carried this saying to the extreme, we would also say that you and I are quite different people at every moment of our lives—for our molecules change quite a bit.

The great systematizer, Aristotle, would see how this is true—but only in a certain respect. He would do this by analyzing how there are different kinds of causes involved in everything—one of which is the matter (which does indeed change).

In the Apology, the trial of Socrates is recounted as he defends himself against his accusers. The course of his speech, he refers to himself as a "gadfly" sent to wake up Athens. The image of the gadfly is used in Greek mythology, but the point in Socrates's use of the expression is that he was sent (by his supposed "spirit guide" who goaded him into practicing philosophy) to question the Athenians and unseat them of their pride and supposed knowledge. He was a kind of "annoyance" meant to pull them down from their conceits.

The Consolation of Philosophy was written by Anicius Manlius Severinus Boethius during his period of imprisonment at the hand of his former "employer", Theodoric the Great. In the text, Boethius is visited by Lady Philosophy, with whom he discusses a variety of Philosophical topics. The work is interspersed with related poetry as well. Throughout their discussions, Boethius is consoled that true felicity is not found in the passing and capricious happenings of this world (and the opinions of those in it).

In Greek, the word Organon means "instrument." The followers of Aristotle came to call his logical writings the Organon because logic is an instrument for all of the other sciences. This canon of logical writings would become a standard canon for teaching logic in the Middle Ages after Aristotle's works were rediscovered. (Only parts of his works survived into the early Middle Ages.) There were other forms of logic that developed after Aristotle, especially that of the Stoics. Likewise, in the Middle Ages, there was the development of numerous logical topics not directly covered by Aristotle. In addition, contemporary logic tends to ignore much of Aristotle, though even it is not without reliance on the old Greek philosopher. 

Interestingly, Aristotle himself thought that he was a pioneer in logic and that he was breaking new ground. Indeed, he says as much in a charming way in his Sophistical Refutations—a treatise dealing with sophistries (i.e. arguments that appear to be valid when they are not).