In affirming that "what is true is the sign of itself and of what is false", Spinoza avoided any problematic which depended on a "criterion of truth … - Benedictus de Spinoza

A passion seizes to be a passion as soon as we form a clear idea of it.

Pantheism is as old as philosophy. It was taught in the old Greek schools — by Plato, by St. Augustine, and by the Jews. Indeed, one may say that Pantheism, under one of its various shapes, is the necessary consequence of all metaphysical inquiry, when pushed to its logical limits ; and from this reason do we find it in every age and nation. The dreamy contemplative Indian, the quick versatile Greek, the practical Roman, the quibbling Scholastic, the ardent Italian, the lively Frenchman, and the bold Englishman, have all pronounced it as the final truth of philosophy. Wherein consists Spinoza's originality? — what is his merit? — are natural questions, when we see him only lead to the same result as others had before proclaimed. His merit and originality consist in the systematic exposition and development of that doctrine — in his hands, for the first time, it assumes the aspect of a science. The Greek and Indian Pantheism is a vague fanciful doctrine, carrying with it no scientific conviction ; it may be true — it looks true — but the proof is wanting. But with Spinoza there is no choice : if you understand his terms, admit the possibility of his science, and seize his meaning; you can no more doubt his conclusions than you can doubt Euclid ; no mere opinion is possible, conviction only is possible.

...Spinozism conquers a place in contemporary philosophy, no longer simply as an historical index of reference but as an operative paradigm. This occurs because Spinozism always represents a full stop in the critique of modernity, for it opposes a conception of the collective subject, of love and the body as powers of presence to the conception of the subject-individual, of mediation and the transcendental, which inform the concept of the modern from Descartes to Hegel and Heidegger. Spinozism is a theory of time torn away from purposiveness, the foundation of an ontology conceived as a process of constitution. It is on this basis that Spinozism acts as the catalyst of an alternative in the definition of the modern. But why should one deprecate a centuries-old position of radical refusal of the forms of modernity by calling it by the feeble name of 'alternative'? [...] Certain contemporary authors have felicitously anticipated our definition of Spinoza's anti-modernity. Thus Althusser: "Spinoza's philosophy introduced an unprecedented theoretical revolution into the history of philosophy, probably the greatest philosophical revolution of all time, to the point that we can regard Spinoza as Marx's only direct ancestor, from the philosophical standpoint." Why? Because Spinoza is the founder of an absolutely original conception of praxis without teleology, because he thought the presence of the cause in its effects and the very existence of structure in its effects and in presence.