Lives and Opinions of Eminent Philosophers by Diogenes Laertius (circa 300AD) is a biography of major Greek philosophers, including Book 10 on Epicurus. Contained within are:
- A letter from Epicurus to Herodotus entitled “A Summary of Physical Nature”
- A letter from Epicurus to Pythocles entitled “A Summary of Phenomena of the Sky”
- A letter from Epicurus to Menoeceus entitled How to Live a Happy Life
- The last will of Epicurus, outlining his final thoughts and disposition of his assets (and care of the children)
Diogenes was at least a fan of Epicurus, if not an Epicurean. Regarding Epicurus, Diogenes writes:
“our philosopher has abundance of witnesses to attest his unsurpassed goodwill to all men – his native land, which honoured him with statues in bronze; his friends, so many in number that they could hardly be counted by whole cities … the School itself which, while nearly all the others have died out, continues for ever without interruption through numberless reigns of one scholarch after another; his gratitude to his parents, his generosity to his brothers, his gentleness to his servants … and in general, his benevolence to all mankind.”
You can read the entire text of Book X on Wikisource1.
You can read more about the book here on Wikipedia2.
1 Lives of the Eminent Philosophers/Book X, https://en.wikisource.org/w/index.php?title=Lives_of_the_Eminent_Philosophers/Book_X&oldid=9192237 (last visited Jan. 6, 2022).
2 Lives and Opinions of Eminent Philosophers, https://en.wikipedia.org/w/index.php?title=Lives_and_Opinions_of_Eminent_Philosophers&oldid=1027395060 (last visited Jan. 6, 2022).