men, in so far as they live in obedience to reason necessarily do only such things as are necessarily good for human nature, and consequently for eac… - Benedictus de Spinoza

Hence it inevitably follows logically, as Engels said, ‘that matter remains eternally the same in all its transformations, that none of its attributes can ever be lost, and therefore, also, that with the same iron necessity that it will exterminate on the earth its highest creation, the thinking mind, it must somewhere else and at another time again produce it.’ That was Spinoza's standpoint, a circumstance that seemingly gave Engels grounds for replying categorically and unambiguously to Plekhanov when he asked: ‘So in your opinion old Spinoza was right in saying that thought and extension were nothing but two attributes of one and the same substance?’ "Of course," answered Engels, "old Spinoza was quite right".’ Spinoza's definition means the following: in man, as in any other possible thinking creature, the same matter thinks as in other cases (other modi) only ‘extends’ in the form of stones or any other ‘unthinking body’; that thought in fact cannot be separated from world matter and counterposed to it itself as a special, incorporeal ‘soul’, and it (thought) is matter’s own perfection. That is how Herder and Goethe, La Mettrie and Diderot, Marx and Plekhanov (all great ‘Spinozists’) and even the young Schelling, understood Spinoza. [...] Spinoza said more than once that it was impermissible to represent thought as attribute in the image and likeness of human thought; it was only the universal property of substance that was the basis of any ‘finite thought’, including human thought, but in no case was it identical with it. To represent thought in general in the image and likeness of existing human thought, of its modus, or ‘particular case’, meant simply to represent it incorrectly, in ‘an incomplete way’, by a ‘model’, so to say, of its far from most perfected image (although the most perfected known to us).

...We know at least since Spinoza that joy and its variant lead to a greater functional perfection, and that sorrow and related effects are unhealthy and should therefore be avoided. But music allows us to feel pain and pleasure simultaneously, both as players, and as listeners. [...] Music to me is sound with thought, and as Spinoza believed that rationality was the saving grace of the human being, then we must learn to look at music like this too.

In Hegel there are three elements, Spinoza's Substance, Fichte's Self-Consciousness and Hegel's necessarily antagonistic unity of the two, the Absolute Spirit. The first element is metaphysically disguised nature separated from man; the second is metaphysically disguised spirit separated from nature; the third is the metaphysically disguised unity of both, real man and the real human species.