I got into reviewing a few classics.
Charles Darwin, On the Origin of Species.
Origin is a fascinating read. People give Galileo and Newton credit for founding true science and its methods, but Darwin earned credit too. He forced us all to understand that we are just animals, despite whatever the holy books say. That was a rough fight, and Darwin won. In so doing, he helped lay down the blueprint for how to do science.
https://www.gutenberg.org/ebooks/1228
Niccolò Machiavelli, The Prince.
This is one of the most maligned pieces of literature ever written. It as coldly logical and sensible as could be imagined. Niccolò had some things to say, and whether or not you agree with his conclusions about how we should act, he is demonstrably correct about how we do act. This is a slim volume, written in direct language, doesn't take too long to absorb.
https://www.gutenberg.org/ebooks/57037
Johnathan Swift, A Modest Proposal
One of the most famous essays ever written. Savage satire that skewers the causes of the famines in Ireland in the 1700s. This is the same guy that wrote Gulliver's Travels, which probably also has more teeth than one might expect upon re-reading it as an adult. Only a few pages long, A Modest Proposal is a master class in effective writing.
https://www.gutenberg.org/files/1080/1080-h/1080-h.htm
Dante Alighieri, The Inferno
Officially known as The Divine Comedy of Dante Alighieri, this is a trilogy about someone losing his way and going to hell. And back. The Inferno is the first book, and unsurprisingly, the Hell bit is the only part really worth reading. To be honest, even just The Inferno is hard slog. It's supposed to be a poem, or at least be in verse of some sort. It was published in 1321. That's a lot of language gap, they simply talked a lot different. Anyway this work is where an awful lot of our conceptions of heaven and hell came from. It's worth the time, if you can stand the very, very old text.
https://www.gutenberg.org/ebooks/41537