Isaac Vossius

First name
Last name
Date of Birth
Date of Death
Born in
Died in

Isaac Vossius studied philosophy in Leiden (1638) under Jacobus Golius. He was the personal librarian (1648) to Queen Christina of Sweden. He lived in London from 1670 until his death in 1689. He was a man of high intellectual reputation with a broad horizon and a multifaceted range of activities (ranging from biblical chronology and geography to the theory of light and microscopes). See: Soll, 2009. Vossius’s impressive collection of manuscripts and books is now kept in Leiden (Derksen, 2012). See: NNBW, vol. 1, cols 1519–25; BBK, vol. 13.

Spinoza met the Dutch scholar and optician Isaac Vossius in 1667 to ask his opinion about the wild story that Johannes Fredericus Schweitzer, a local anti-Cartesian physician and alchemist, had successfully effected a transmutation of lead into gold. That Spinoza wanted to consult Vossius about the alleged transmutation cannot be seen as a surprise. Apart from Vossius’s solid reputation in the sciences—he was considered in his own time as one of the most pivotal curieux in the European world of learning—, he is also reported as having cultivated an avid interest in alchemy. Moreover, he also owned a massive collection of alchemical manuscripts (Boeren, 1975). When Spinoza visited Vossius, it soon turned out that he was critical of Schweitzer’s abilities as a physician and he saw his qualities as an alchemist probably in the same light of mistrust. From his reaction to Spinoza’s questions about the alleged transmutation, it turns out that Vossius judged the whole story and Schweitzer’s predilection for alchemy to be one big mischievous deception. Moreover, the letter to Jelles of the 25th informs us that he even made fun of Spinoza’s fascination for the story of Schweitzer. When I asked Vossius to give a comment on the rumour, Spinoza informs his Amsterdam correspondent, he ‘laughed heartily and was surprised that I would ask him about these trifles’.

Unfortunately, in his response to Jelles Spinoza only briefly refers to the rendezvous with Vossius. Nonetheless, the rejoinder also suggests that during his visit they spoke about many more than Schweitzer’s claim alone. In it, Spinoza tells his Jelles that they had discussed a range of other topics and writes thus: ‘—not to relate in a letter everything we talked about’ (G 4/196). Yet, it is in any case likely that they talked about the trending issue of optics. In the mid-1660s, only a select group of Dutch scientists and amateurs involved in physics cultivated a keen interest in theoretical and practical optics. Also Spinoza himself inhabited this experimental world in which kindred spirits passionately tried piecing together all aspects of physical phenomena proper. Moreover, it is known that during the mid-1660s Spinoza was mastering the craft of grounding lenses for microscopes and he was also busy (with Johannes Hudde) constructing refracting telescopes (1666.[06].[00], Ep 36). 

One may ask how and when relations between Vossius and Spinoza exactly emerged and who may have been their intermediary. Perhaps, Spinoza was introduced to Vossius by one of the members of the Huygens family. Because both the Huygens family as well as Vossius moved in the elitist ‘circle’ of Dutch scientists working in the field of optics and resided in The Hague, it is almost inconceivable that Spinoza’s work in optics done in nearby Voorburg was fully unknown to Vossius. This would indicate that issues of optical importance were perhaps one of the topics he discussed with Vossius when he called on him to learn more about Schweitzer’s alleged transmutation.

Spinoza also shared some of Vossius critical views on matters philosophical or theological. Like Spinoza, Vossius also rejected contingency and chance (Vossius, 1686, p. 138). The scholar owned an impressive theological book collection and made an important contribution to biblical chronology in editing Dissertatio de vera aetate mundi (Dissertation on the True Age of the World). That work concerns an impressive philological study partly written in reaction to the controversial pre-Adamite theory as put forward in 1655 in Prae-Adamitae/Systema theologicum, in which by Isaac de la Peyrère discredits the historical accuracy of the Old Testament. With respect to Vossius’s own religious convictions, however, he is reported as being someone who had no confidence whatsoever in revealed religion or the divine authority of the Bible (Van Bunge, 2001, p. 160; Jorink, 2008b, pp. 441-5; Jorink, 2012, pp. 271–6).

In the Appendix of Observationes ad Pomponium Melam de situ orbispublished by Vossius in 1686, he briefly refutes Spinoza’s radical biblical criticism and his denial that Moses wrote all, or even most of the Torah verbatim (Vossius, 1686, pp. 111-2). It may be conjectured that Vossius read the Tractatus theologico-politicus.



Johannes Fredericus Schweitzer


Queen Christina of Sweden


Menasseh Israel, ben


Christina Wasa


Gerardus Johannes Vossius


Andreas Colvius


René Descartes


Hugo Grotius


Claude Saumaise


Benedictus Spinoza, de


Jacobus Golius