Spinoza, like Socrates and Plato, believes that all wrong action is due to intellectual error: the man who adequately understands his own circumstances will act wisely, and will even be happy in the face of what to another would be misfortune.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“The last two books of the Ethics, entitled respectively “ Of human bondage, or the strength of the emotions ” and “ Of the power of the understanding, or of human freedom, ” are the most interesting. We are in bondage in proportion as what happens to us is determined by outside causes, and we are free in proportion as we are self-determined. Spinoza, like Socrates and Plato, believes that all wrong action is due to intellectual error: the man who adequately understands his own circumstances will act wisely, and will even be happy in the face of what to another would be misfortune. He makes no appeal to unselfishness; he holds that self-seeking, in some sense, and more particularly self-preservation, govern all human behaviour. “ No virtue can be conceived as prior to this endeavour to preserve one’s own being. ”” source