...The proposal to think the determination of the elements of a whole by the structure of the whole posed an absolutely new problem in the most theor… - Benedictus de Spinoza

In the strident world of seventeenth-century philosophy, the mind-body problem was not a word puzzle that could be safely relegated to undergraduate classes. For men such as Descartes, Malebranche, and Leibniz, solving the mind-body problem was vital to preserving the theological and political order inherited from the Middle Ages and, more generally, to protecting human self-esteem in the face of an increasingly truculent universe. For Spinoza, it was a means of destroying that same order and discovering a new foundation for human worth.

Note II. — From all that has been said above it is clear, that we, in many cases, perceive and form our general notions: — (1.) From particular things represented to our intellect fragmentarily, confusedly, and without order through our senses (II. xxix. Coroll.); I have settled to call such perceptions by the name of knowledge from the mere suggestions of experience.4 (2.) From symbols, e.g., from the fact of having read or heard certain words we remember things and form certain ideas concerning them, similar to those through which we imagine things (II. xviii. note). I shall call both these ways of regarding things knowledge of the first kind, opinion, or imagination. (3.) From the fact that we have notions common to all men, and adequate ideas of the properties of things (II. xxxviii. Coroll., xxxix. and Coroll. and xl.); this I call reason and knowledge of the second kind. Besides these two kinds of knowledge, there is, as I will hereafter show, a third kind of knowledge, which we will call intuition. This kind of knowledge proceeds from an adequate idea of the absolute essence of certain attributes of God to the adequate knowledge of the essence of things. I will illustrate all three kinds of knowledge by a single example. Three numbers are given for finding a fourth, which shall be to the third as the second is to the first. Tradesmen without hesitation multiply the second by the third, and divide the product by the first; either because they have not forgotten the rule which they received from a master without any proof, or because they have often made trial of it with simple numbers, or by virtue of the proof of the nineteenth proposition of the seventh book of Euclid, namely, in virtue of the general property of proportionals. But with very simple numbers there is no need of this. For instance, one, two, three, being given, everyone can see that the fourth proportional is six; and this is much clearer, because we infer the fourth number from an intuitive gr

...Now Spinoza, my master and model in respect to the first point [the natural basis of morality], does not satisfy me on the second [the humane possibilities, the "types of excellence towards which life may be directed"]; and I will take this opportunity, since I may not have any other, of clearing my conscience of ambiguity in that respect. The complete moralist must not only be sound in physics, but must be inwardly inspired by a normal human soul and an adequate human tradition; he must be a complete humanist in a complete naturalist. Spinoza was not only a complete naturalist but, by a rare combination, also a spiritual man, seeing and accepting the place of the human heart in the universe; accepting it not grudgingly or viciously or frivolously, as your worldling does, but humbly and joyously: humbly in that he asked to be nothing more than he was, and joyously because what he was allowed him, in spirit, to salute and to worship every form of the good. Nevertheless, Spinoza was not a complete humanist. He had no idea of human greatness and no sympathy with human sorrow. His notion of the soul was too plebeian and too quietistic. He was a Jew not of Exodus or Kings but of Amsterdam. He was too Dutch, too much the merchant and artisan, with nothing of the soldier, the poet, the prince, or the lover. [...] He was virtuous but not normal. [...] He was a genius; but as a guide in the spiritual life, he was narrow and inadequate.