Spinoza: the absolute philosopher, whose Ethics is the foremost book on concepts. - Benedictus de Spinoza

I think back to the last discussion I had with the great conductor Otto Klemperer. We talked about Spinoza and he said “Spinoza's Ethics is the most important book ever written”. Klemperer was, as we know, Jewish. At the age of 22 he converted to Christianity because he believed that only as a Christian could he conduct Bach's St Matthew Passion. Many years later, after the War, when Klemperer had already reached old age, he converted back to Judaism. And the reason he gave was Spinoza's Ethics. Perhaps the most important Jewish philosophy. Questions about Jewish ethics and morals and “What is being Jewish?” were long identified as being a minority. The traditional thinking and perceived identity of the Jewish people in its 2,000 year history was as a minority. Historically the Jews were integrated into social and cultural life but tragically persecuted under the Spanish Inquisition and the tyranny of Adolf Hitler. What is special about Spinoza's philosophy is that, despite persecution, abuse and alienation, his thinking was never based on the premise of Jews being a minority. That is precisely why his philosophy is so contemporary, now that the Jewish people have their own state, i.e. are no longer a minority. Spinoza's Ethics remains a potent formula for creating intellectual and moral unity among the Jews.

...The teaching of Spinoza, the product of the Jewish genius and modern science [Wissenschaft], does not stand in contradiction with the Jewish teaching of unity - at most it may contradict its rationalistic and super-naturalistic approach.

Spinoza, then, emerged as the supreme philosophical bogeyman of Early Enlightenment Europe. Admittedly, historians have rarely emphasized this. It has been much more common, and still is, to claim that Spinoza was rarely understood and had very little influence, a typical example of an abiding historiographical refrain which appears to be totally untrue but nevertheless, since the nineteenth century, has exerted an enduring appeal for all manner of scholars. In fact, no one else during the century 1650–1750 remotely rivalled Spinoza's notoriety as the chief challenger of the fundamentals of revealed religion, received ideas, tradition, morality, and what was everywhere regarded, in absolutist and non-absolutist states alike, as divinely constituted political authority.