...Spinoza became aware of this in a way that made him show his true colours (to the annoyance of his critics, who systematically attempt to misunderstand him on this point, Kuno Fischer, for example), when, one afternoon, rummaging around among who knows what memories, he turned his attention to the question of what actually remained for him, himself, of that famous morsus conscientiae - he who had relegated good and evil to man's imagination and angrily defended the honour of his 'free' God against the blasphemists who asserted that God operates everything sub ratione boni ('but that would mean that God is subject to fate and would really be the greatest of all absurdities' –). For Spinoza, the world had returned to that state of innocence in which it had lain before the invention of bad conscience: what had then become of morsus conscientiae?...

[T]hese instances are enough to show, that the body can by the sole laws of its nature do many things which the mind wonders at.

For Spinoza, philosophy originates in the very personal... feeling of emptiness that in the philosophical tradition has earned the distinguished name of contemptu mundi, the contempt for worldly things, or, better, vanitas. ...Spinoza says that... success in life is just a postponement of failure; ...pleasure is just a fleeting respite from pain; and... the objects of our striving are vain illusions. ...
The feeling of vanitas Spinoza describes is... a dire encounter with the prospect of descent into absolute nothingness, a life without significance coming to a meaningless end. ...The experience Spinoza records... establishes... the moment of extreme doubt , fear, and uncertainty that precedes the dawn of revelation. ...the journey ...is one trodden by poets, philosophers, and theologians too numerous to mention, who for millennia have recorded this feeling that life is a useless passion, a wheel of ceaseless striving, a tale told by an idiot, full of sound and fury, signifying nothing, and so on.

Just as Herder's cosmopolitanism allowed him to become very sympathetic to Judaism as a religion and cultural tradition, so it also allowed him to become a great admirer of the most important Jewish philosopher of the modern period: Spinoza. As is well known, Herder's appropriation (and modification) of the metaphysical monism of Spinoza's Ethics in God: Some Conversations (1787) played a central role in generating the forms of neo-Spinozistic metaphysical monism that later dominated German Idealism and German Romanticism. But Herder's interest in and sympathy with Spinoza in fact reach much further back in time than that work, to the late 1760's, and his intellectual debts to Spinoza extend well beyond the principle of metaphysical monism. Thus, another important debt lies in the anti-dualistic and deterministic philosophy of mind that Herder presented, with explicit mention of Spinoza, in On the Cognition and Sensation of the Human Soul (1778), which is again heavily indebted to the Ethifcs. Moreover, even before Herder was influenced by the Ethics in the ways just mentioned, he was influenced by the Tractatus. Thus, another major area in which he owes debts to Spinoza is the theory of interpretation, especially biblical interpretation, where he borrowed principles from the Tractatus from the late 1760's on. And yet another debt can be seen in Herder's early turn, in about 1770, away from monarchy as a constitutional ideal towards the ideals of democracy and liberalism – for that turn was influenced by Spinoza's championing of the latter ideals in the Tractatus. Putting these cases together, one can indeed see that Herder beginning in the late 1760's engaged in a sort of progressive appropriation of increasingly fundamental levels of Spinoza's thought: first principles of interpretation, then political ideals, then philosophy of mind and metaphysics. All of the principles in question went on to play important roles within German Idealism and German Romanticism. Spinoza's contribution to those movements was thus far greater than has usually been realized.

It was on Spinoza that I worked the most seriously according to the norms of the history of philosophy — but he more than any other gave me the feeling of a gust of air from behind each time you read him, of a witch's broom which he makes you mount. We have not yet begun to understand Spinoza, and I myself no more than others.

The movement of modern philosophy is back towards the position of the old Ionian philosophers, but strengthened and clarified by sound scientific ideas. If I publish my criticism on Comte, I should have to re-write it as a summary of philosophical ideas from the earliest times. The thread of philosophical development is not on the lines usually laid down for it. It goes from Democritus and the rest to the Epicureans, and then the Stoics, who tried to reconcile it with popular theological ideas, just as was done by the Christian Fathers. In the Middle Ages it was entirely lost under the theological theories of the time; but reappeared with Spinoza, who, however, muddled it up with a lot of metaphysics which made him almost unintelligible.

Spinoza's ethics has nothing to do with a morality; he conceives it as an ethology, that is, as a composition of fast and slow speeds, of capacities for affecting and being affected on this plane of immanence. That is why Spinoza calls out to us in the way he does: you do not know beforehand what good or bad you are capable of; you do not know beforehand what a body or a mind can do, in a given encounter, a given arrangement, a given combination.

It is to the highest credit of the philosophy of the time that it did not let itself be led astray by the restricted state of contemporary natural knowledge, and that — from Spinoza down to the great French materialists — it insisted on explaining the world from the world itself and left the justification in detail to the natural science of the future.

The greatest secret of monarchic rule...is to keep men deceived and to cloak in the specious name of religion the fear by which they must be checked, so that they will fight for slavery as they would for salvation, and will think it not shameful, but a most honorable achievement, to give their life and blood that one man may have a ground for boasting.

[We] will discuss Soul and Body, the doctrine of God, and Ethics. ...We shall find that Leibniz no longer shows great originality, but tends, with slight alterations of phraseology, to adopt (without acknowledgment) the views of the decried Spinoza. We shall find also many more minor inconsistencies than in the earlier part of [Leibniz's] system, these being due chiefly to the desire to avoid the impieties of the Jewish Atheist, and the still greater impieties to which Leibniz's own logic should have led him.

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

Can any one doubt that if the noblest saint among the Buddhists, the best Mahometan, the highest Stoic of Athens, the purest and wisest Christian, — Buddha and Menu in India, Confucius in China, Spinoza in Holland, could somewhere meet and converse, — they would all find themselves of one religion, — would find themselves denounced by their own sects, and sustained by these believed adversaries of their sects.

The brilliance of the solution of the problem of the relation of thinking to the world of bodies in space outside thought (i.e. outside the head of man), which Spinoza formulated in the form of the thesis that thought and extension are not two substances, but only two attributes of one and the same substance, can hardly be exaggerated. This solution immediately rejected every possible kind of interpretation and investigation of thought by the logic of spiritualist and dualist constructions, so making it possible to find a real way out both from the blind alley of the dualism of mind and body and from the specific blind alley of Hegelianism. It is not fortuitous that Spinoza’s profound idea only first found true appreciation by the dialectical materialists Marx and Engels. Even Hegel found it a hard nut to crack. In fact, on the decisive point, he returned again to the position of Descartes, to the thesis that pure thought is the active cause of all the changes occurring in the ‘thinking body of man’, i.e. in the matter of the brain and sense organs, in language, in actions and their results, including in that the instruments of labour and historical events.