"The difficulty begins with the problem that there are several Spinozas with which to reckon, at least four by my count. The first is the accessible Spinoza, the radical religious scholar who dis­agrees with the churches of his time, presents a new conception of God, and proposes a new road to human salvation. Next comes Spinoza as political architect, the thinker who describes the traits of an ideal democratic state populated by responsible, happy citi­zens. The third Spinoza is the least accessible of the set: the philosopher who uses scientific facts, a method of geometric demonstration and intuition to formulate a conception of the universe and the human beings in it. Recognizing these three Spinozas and their web of depen­dencies is enough to suggest how convoluted Spinoza can be. But there is a fourth Spinoza: the protobiologist. This is the biological thinker concealed behind countless propositions, axioms, proofs, lemmas, and scholia. Given that many of the advances on the sci­ence of emotions and feeling are consonant with proposals that Spinoza began to articulate, my second purpose in this book is to connect this least-known Spinoza to some of the corresponding neurobiology of today. But I note, again, that this book is not about Spinoza's philosophy. I do not address Spinoza's thinking outside of the aspects I regard as pertinent to biology. The goal is more modest. One of the values of philosophy is that throughout its history it has prefigured science. In turn, I believe, science is well served by recognizing that historical effort."