Some classical texts for free, teaching about philosophy, morals, and stoicism. All books are highly rated and free at the time of posting.
Meditations: https://www.amazon.com.au/Meditations-Marcus-Aurelius-ebook/dp/B094RZ8J7C
Seneca Six Pack 2: Six More Essential Texts: https://www.amazon.com.au/Seneca-Six-Pack-Essential-Texts-ebook/dp/B072PX87TK
An Enquiry Concerning the Principles of Morals: https://www.amazon.com.au/Enquiry-Concerning-Principles-Mora…
Evolution and Ethics: https://www.amazon.com.au/Evolution-Ethics-Thomas-Henry-Huxl…
US Links:
Walden: not available for free on the US website
Meditations: https://www.amazon.com/Meditations-Marcus-Aurelius-ebook/dp/B094RZ8J7C
Seneca Six Pack 2: Six More Essential Texts: https://www.amazon.com/Seneca-Six-Pack-Essential-Texts-ebook/dp/B072PX87TK
An Enquiry Concerning the Principles of Morals: https://www.amazon.com/Enquiry-Concerning-Principles-Morals-…
Evolution and Ethics: https://www.amazon.com/Evolution-Ethics-Thomas-Henry-Huxley-…
Enjoy!
Anyone wanting to read Thoreau but finding Walden a bit long might consider reading Civil Disobedience instead, or first. It's short, can be downloaded in many places as text or audio - easy listening in the car or on the train over a few short trips. Highly influential on some big names including Mahatma Gandhi and MLK Jr.