"The Ethics is a book of concepts (the second kind of knowledge), but also of affects (the first kind) and percepts (the third kind) too. Thus the paradox in Spinoza is that he's the most philosophical of philosophers, the purest in some sense, but also the one who more than any other addresses non-philosophers and calls forth the most intense non-philosophical understanding. That is why absolutely anyone can read Spinoza, and be very moved, or see things quite differently afterward, even if they can hardly understand Spinoza's concepts. Conversely, a historian of philosophy who understands only Spinoza's concepts doesn't fully understand him."