Spinoza's philosophy introduced an unprecedented theoretical revolution in the history of philosophy, probably the greatest philosophical revolution … - Benedictus de Spinoza

I am utterly amazed, utterly enchanted! I have a precursor, and what a precursor! I hardly knew Spinoza: that I should have turned to him just now, was inspired by "instinct". Not only is his overtendency like mine — namely, to make all knowledge the most powerful affect — but in five main points of his doctrine I recognize myself; this most unusual and loneliest thinker is closest to me precisely in these matters: he denies the freedom of the will, teleology, the moral world-order, the unegoistic, and evil. Even though the divergencies are admittedly tremendous, they are due more to the difference in time, culture, and science. In summa: my lonesomeness, which, as on very high mountains, often made it hard for me to breathe and make my blood rush out, is now at least a twosomeness. Strange!

The philosopher John Toland, in the early 18th century, insisted that the terms 'Spinozism' and 'pantheism' are synonymous. Toland says that "Moses was, to be sure, a Pantheist, or, if you please, in more current terms, a Spinosist", while Spinoza's pantheism was taken for granted by Moses Mendelssohn, Gotthold Lessing and Friedrich Jacobi, in their famous Pantheismusstreit of 1785. More recently, this interpretation also appears in both the scholarly literature and popular representations of Spinoza's thought. In the recently published Cambridge Dictionary of Philosophy we read that "Spinoza is the most distinguished pantheist in Western philosophy". But the problem with calling Spinoza a 'pantheist' is that pantheism is still a kind of theism.

The question of Spinozism is indeed central and indispensable to any proper understanding of Early Enlightenment European thought. Its prominence in European intellectual debates of the late seventeenth and early eighteenth century is generally far greater than anyone would suppose from the existing secondary literature; one of the chief aims of this present study is to demonstrate that there has been a persistent and unfortunate tendency in modern historiography to misconstrue and underestimate its significance. Admittedly, the term 'Spinosisme' as used in the French Enlightenment, or Spinozisterey, as it was called in Germany, was frequently employed, as in the campaign against Montesquieu, rather broadly to denote virtually the whole of the Radical Enlightenment, that is, all deistic, Naturalistic, and atheistic systems that exclude divine Providence, Revelation, and miracles, including reward and punishment in the hereafter, rather than strict adherence to Spinoza's system as such. Yet this does not mean that it was a vague or meaningless usage. On the contrary, the extremely frequent and extensive use of the terms Spinozism and Spinosistes in Early Enlightenment discourse, not least in Bayle, who devoted the longest single article in his Dictionnaire historique et critique to the subject of Spinoza and Spinosisme, is precisely intended to connect—and with considerable justification, as we shall see—Spinoza's philosophy with a wide-ranging network of other radical thought.