I read this book in college (1970s), but the bit that sticks in my memory was his discussion of observations through Galileo&#x27;s telescope. His observation, and others&#x27; confirmation, of Jupiter&#x27;s moons, the phases of the planets, and other phenomena helped end the Ptolemaic era, and had a profound effect on the development of science. Feyerabend starts with the idea that &quot;anything goes&quot; and tries to support it by describing some anecdotes of people who looked through Galileo&#x27;s telescope and said they couldn&#x27;t see anything. He thinks these anecdotes should be weighted equally with the body of detailed astronomical observation, and thinks it was arbitrary to base scientific models on observations of what, after all, were real things. He starts with his conclusion and finds anecdotes to support it. I suspected at the time that he wasn&#x27;t even taking himself seriously, but plenty of other people seem to have been.