Spinoza is fascinating and his arguments powerfully persuasive and astonishingly relevant today. But he is tough, and at first glance, maybe crazy. Nadler is a Spinoza specialist who wrote a wonderful intellectual biography published by Cambridge. He does a great job here of introducing and clarifying the ideas and showing the precise historical antecedents in Descartes, etc. Really fine work and especially when compared to other introductions in this series (for instance, the Descartes' Meditations and Aristotle's Ethics intros are TERRIBLE). I've been studying Spinoza for years but this book still taught me a few things.Related readings: Jonathan Israel's "Radical Enlightenment." A huge history book but really really good and it shows how Spinoza was everywhere. The author also put out a recent translation of Spinoza's Theological-Political Treatise available also by Cambridge U. Press, and which is a great companion to the ethics (maybe even a better place to start with Spinoza than the tricky ethics).If you want to go from Nadler's fine intro to the next step, read H. A. (Harry Austryn) Wolfson's canonical, authoritative, unparalleled historical study "The Philosophy of Spinoza." It's not in print but copies abound. There are two volumes (the unified edition is not worth it, it will crumble to pieces). Springing for hard-back is worth it, as you'll read the book many times. It is a fantastic resource on Spinoza. If you read French then Martial Geurault is the standard. For contemporary continental takes on Spinoza, see "The New Spinoza." Etienne Balibar's "Spinoza and Politics" is great too. Many people like Deleuze's reading of Spinoza - he has two books, a big one and a little one. They are indeed interesting, but they represent Deleuze: he works from Spinoza's ideas in undoubtedly fascinating ways, but it's not strictly Spinoza. The Cambridge Companion to Spinoza is not good. Ignore Bennett unless you are an analytic philosopher (in which case, what are you doing reading Spinoza? He's crazy!)