I can heartily recommend this text to Latin learners. It was written in 625, and is a kind of account of everything that is known - it covers language (everything from the history of languages, the varieties of Latin and Greek, the fact that they used to put Th after a person’s name on a list to mark them as dead, metric schemas for poetry, etymology), music, astronomy, medicine, geography, logic. Extremely clear and straight-forward Latin (I basically read through LLPSI, then worked through Harry Potter, and could skim through most of this easily, while not getting all the details, still really enjoying it).
It’s both a great read for quantity of easy Latin, but also a super-interesting look at what was known at that time. He quotes extensively from Latin and Greek sources, and this is a book that was used widely in education for a 1000 years.
I was able to get a copy through Interlibrary Loan, but there are two digital versions available, both linked here. https://en.wikipedia.org/wiki/Etymologiae