Read Tacitus' description of the Death of Seneca and Book One of M. Aurelius' Meditations. Find quotes within those two texts that help explain what Stoicism is all about.

Quotes from The Death of Seneca and Book One of Marcus Aurelius:

"Upon this the tribune asserted that he saw no signs of fear, and perceived no sadness in his words or in his looks."(The Death of Seneca)


"At the same time he called them back from their tears to manly resolution, now with friendly talk, and now with the sterner language of rebuke." (The Death of Seneca)


"Even at the last moment his eloquence failed him not; he summoned his secretaries, and dictated much to them which, as it has been published for all readers in his own words, I forbear to paraphrase." (The Death of Seneca)


"From my governor, to be neither of the green nor of the blue party at the games in the Circus, nor a partizan either of the Parmularius or the Scutarius at the gladiators' fights; from him too I learned endurance of labour, and to want little, and to work with my own hands, and not to meddle with other people's affairs, and not to be ready to listen to slander."(Book One of Marcus Aurelius)


"His fame rest, above all, on his Meditations, a series of reflections, strongly influenced by Epictetus, which represent a Stoic outlook on life." (Book One of Marcus Aurelius)

"From Alexander the Platonic, not frequently nor without necessity to say to any one, or to write in a letter, that I have no leisure; nor continually to excuse the neglect of duties required by our relation to those with whom we live, by alleging urgent occupations."(Book One of Marcus Aurelius)

Stoicism was a Hellenistic Philosophy in the city of Athens by a man named Zeno of Citium. Stoics considered emotions to be an error of judgement meaning that no matter what the situation is a Stoic may not show any feelings at all. Stoics have a fundamental concept called Prohairesis. This concept states that nothing is good or bad. Meaning with Prohairesis a person can rationally react to impression that has happened upon him/her. A stoic believes that only a sage is truly free. To a Stoic a Sage is a person who was morally and intellectually perfect. Stoicism was viewed by the Fathers of the Church as a pagan philosophy and as a consequence all of it's philosophy schools were to be shut down by the order of Emperor Justinian I.

Sources:
Bunson, Matthew, A Dictionary of the Roman Empirepage 382
Fitch, John (2008). Seneca. City: Oxford University Press, USA. p. 32