Wherever possible Spinoza's own chapter headings have been retained; and some of the sectional headings have either been taken from, or have been based upon expressions in the text. It would have been more in keeping with contemporary form to use the title _On Historical Method_ or _The New History_ instead of _Of the Interpretation of Scripture_; a chapter on _Race Superiority_ would sound more important than one on _The Vocation of the Hebrews_; but such modernizing changes were not made because the aim has been to give the reader a text as faithful to the original as the character of this volume would allow. The selections have been taken from Elwes' translation of the _Tractatus Theologico-Politicus_, _A Political Treatise_ and the _Improvement of the Understanding_; and from White's translation of the _Ethics_. These translations are no longer in copyright and hence it was not necessary to secure permission from the publishers to use them. Nonetheless, grateful acknowledgment is their just due. White, in his translation, uses, not altogether without reason, the stilted term "affect" instead of the natural English term "emotion." "Affect" is closer to the Latin and it more clearly indicates the metaphysical status of the emotions as "modes" or "affectiones" of Substance. Still, practically no one has followed White in his usage. The reasons are not difficult to discover. Besides being a stilted term, having no legitimate English status, "affect" very often makes the text extremely obscure, even unintelligible to one who has no antecedent knowledge of it, because besides having also its ordinary English meaning, "affect" is used by White to mean "mode" or "modification" ("affection") as well. In the circumstances, therefore, I thought it advisable to change "affect" to "emotion" and "affection" to "modification" or "mode." I also corrected White's translation of the Definition of Attribute by deleting the word "if." In spite of the need for these changes, it was desirable to use White's translation because it is the most accurate and elegant extant. Furthermore, in both White and Elwes I have consistently capitalized the term Nature, in accordance with Spinoza's Latin text; White and Elwes capitalize it only desultorily. I have made some slight changes in Elwes' mid-Victorian punctuation and White's all-too-faithful paragraphing. The Latin paragraphs of the _Ethics_ are extremely long. These changes are all external and as far as I can see thoroughly legitimate as well as justified. The very slight and very occasional internal changes I have made--other than those already accounted for--I have indicated by square brackets.