Ernst Hessen-Rheinfels-Rotenburg, von

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Hessen-Rheinfels-Rotenburg, von
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Landgrave Ernst von Hesse-Rheinfels-Rotenburg was from 1649 to 1658 his death Landgrave of Hesse-Rheinfels and from 1658 until his death Landgrave of Hesse-Rheinfels-Rotenburg. He was a correspondent of Leibniz and friend of the latter’s erstwhile patron, the Hessian Count Von Boineburg. He embarked upon a military career in his younger years. In 1652, he converted with his wife Maria Eleonore von Solms-Hohensolms-Lich (1632) to Roman Catholicism.

An indirect account of the rendezvous between Leibniz and Spinoza is included in a letter Leibniz wrote on 4/14 August 1683 to Von Hessen-Rheinfels-Rotenburg. Anxious to reveal himself in this letter as an admirer of Spinoza’s towering biblical and metaphysical notions, Leibniz presented himself to his new patron as a fierce critic of Spinoza’s metaphysical reasoning and told him that he had met him only ‘several hours’. In the same letter, he even qualifies Spinoza as a mediocre philosopher who would have possessed only an average knowledge of ‘analysis and geometry’. He adds to this, though, that he was an excellent optician skilled in making ‘glasses and microscopes’ (cf. Malcolm, 2003, p. 227). Leibniz writes:

With respect to Spinoza who mr. [Antoine] Arnauld calls the most impious and the most dangerous man of this century. He is truly an atheist, that is to say, he does not admit providence to be the dispenser of good and evil in righteousness, and [he] beliefs to have proof [of it]. The God who he parades, is not like ours [and] he makes no judgement nor [has] a will. He [also] has a pleasant stand on the immortality of the soul, more particularly he conceives this Platonic idea of my being which is undoubtedly also eternal as [is] a circle or a triangle, [and] that is our proper immortality. One needs to perfection in every sort of virtue in order to leave behind an eternal essence or a more perfect Platonic idea at death. As if this idea is not already in nature itself. [And] it is that I need to be like [nature] or not. And if it would serve me after my death, if I am nothing more, to have resembled this beautiful idea. These very strange thoughts are adjusted in such a way in his posthumous work on God, which they believe says completely something else. Nevertheless, although he makes great noise with his demonstrations, he is far from knowing how to demonstrate [them] and he has not more than a mediocre knowledge of analysis and geometry. And what he better knows is how to make glasses and microscopes. I have spent a couple of hours with him whilst passing via The Hague and I learned the rest from one of his followers with whom I came rather familiar with.

Source: Leibniz to Ernst von Hessen-Rheinfels-Rotenburg (n. XXX), 4/14 August 1683; Leibniz, AA, 2:1, p. 841, no. 241.

Although it appears that both giants seemed to have enjoyed each other’s company and their inspiring conversations, Leibniz deliberately failed to pass Spinoza the (now lost) letter which Oldenburg (> 1676.10.18*) had entrusted him during their rendezvous in London.


Gottfried Wilhelm Leibniz


Johann Christian Boineburg, von