This Humanities course is a "survey course" as schools call them. We cover roughly 4,000 years of history between August and May. We touch upon many of the most important people, books, and events. But we cannot do it in depth: we can merely give you a brief glimpse. When you get to the university, you can choose to take in-depth classes in these various subjects, where you will cover much less material, but cover it much more thoroughly.
In such a survey course, one necessary compromise is to read excerpts from famous texts. There isn't time to read everything every written by Plato, Aristotle, Cicero, Thucydides, Shakespeare, and all the other pivotal thinkers. So we read only brief selections from their writings. And this is where you have to do some critical thinking about "spin".
For example, depending on which pages you read, you can make Thucydides seem either like a spokesman for noble morality of the ancient Greeks, or a social critic denouncing their mercenary blood-thirstiness.
Depending on which chapters of the "Republic" you read, Plato can seem either like a proto-Marxist social engineer, or a other-worldly observer of philosophical abstractions.
So, while you think about what you're reading, remember to also think about what you're NOT reading.