For me it was through Deleuze's course on Spinoza. Stumbled upon it. Thought "well, idk anything about this, I might as well listen to it in the background while playing Warframe".
I ended up.. not playing a lot of Warframe..
It is mentioned in the P G Wodehouse story Joy In The Morning, which I read in my teens. I knew absolutely nothing about Spinoza at the time, but happened to find a copy in a s/h bookshop very shortly after reading the Wodehouse tale and picked it up out of curiosity. I skimmed a few pages then but got about as much from it at the time as Bertie Wooster did, I expect.
It was a long while later, when I had read a reasonable amount of other philosophy, that I returned and actually found value in it.
Thanks for sharing! Out of curiosity, could you tell a bit more about this book, Joy in the morning?
Joy in the Morning is a comic novel: one of P G Wodehouse's many Jeeves and Wooster tales.
Bertie Wooster - who is not remotely interested in philosophy or any other intellectual pursuits - picks up a copy of the Ethics as a gift for his valet, the much wiser and more knowledgeable Jeeves, which leads to a misunderstanding that develops the plot. As usual, Wooster ends up in a variety of awkward social situations and Jeeves saves the day. The characer of Jeeves is mentioned to have an appreciation of Spinoza a couple of times elsewhere in these stories, but without any detail. In this particular tale, the book could just as easily been any other 'improving' work. Nothing other than the name is mentioned.
I first heard of Spinoza through his standing up to the authorities. Cut off from his Jewish community, etc. Then I read his sCaNdAlOuS theories, and found them to be not terribly scandalous.