Benedict (Baruch) de Spinoza (1632–1677) stands out as a loner among seventeenth century thinkers. He was excommunicated from the Jewish community in Amsterdam for his unorthodox ideas. After that, he had few contacts with other Jews, but because he was a Jew his Dutch acquaintances were not friendly to him.

In 1660, he moved from Amsterdam to Rijnsburg and then to Voorburg. In 1663, he wrote about Descartes’ philosophy in Renati Descartes Principiorum Philosophiae, Pars I et II. His Tractatus Theologico Politicus was published anonymously in 1670. He was then offered the chair of philosophy at Heidelberg University, in 1673, but he turned it down because he did not want to jeopardize his peace of mind. He thought that academics were constantly arguing among themselves and engaging in petty disputes and grudges. He knew Gottfried Leibniz (1646–1716) and corresponded with the Royal Society members Henry Oldenburg and Christian Huygens.

Spinoza’s Ethics (1677) was published after his death, as was his Tractatus de Intellectis Emendatione (1677). That Spinoza preferred to think on his own, with little outside influence, made his work very distinctive, but it also was part of the reason for a prolonged lack of recognition of him as a philosopher.