Truth, adequacy and error, the Mind-Body relation and the meaning of "having" an idea are issues still at the centre of philosophical debate. Spinoza belongs to those past masters whose work always inspires renewed insights on these as on other philosophical issues. This volume revolves around part II of Spinoza's "opus magnum", the "Ethics" where he offers his theory of knowledge and the human mind. Stuart Hampshire writes about "Truth and Correspondence"; Alexandre Matheron discusses "Ideas of Ideas and Certainty"; Alan Donagon writes on "Language, Ideas and Reasoning"; Jonathan Bennett tackles the difficult one substance-two attributes issue; and Yirmiyahu Yovel analyzes "common notions" and error. Papers are also presented by Jean-Luc Marion, Pierre-Francois Moreau, Guttorm Floistad, Wallace I. Matson, Wim Klever, Elhanan Yakira, Marcelo Dascal, Wolfgang Bartuschat, Amihud Gilead and Filippo Mignini. This work is based on the second Jerusalem Conference (1989). Each conference in this series, and the ensuing volume, focuses on a specific "family" of issues: the first five follow Spinoza's own division in his "Ethics", and the other two deal with Spinoza's social and political theory and his life and sources. This volume should be of interest to Spinoza students and scholars.