I have looked on the Internet about books with no punctuation marks and found a post by Thomas Musselman at Quora:
Punctuation is a post-3rd Century invention so when you read older texts you are reading them with someone sticking in punctuation that didn’t exist when the writer wrote it or his first readers read it. Cicero, e.g., hated marks showing paragraph changes. Purists thought you just should know when to break (from practice reading the text and reading aloud).
Does anybody know where to read the respective passage by Cicero?
2022-06-13: Now answered on Philosophy.StackExchange: q/99837