A series of letters between Benedict de Spinoza and people like Henry Oldenburg, Lewis Meyer, Simon de Vries, Peter Balling, William de Blyenbergh, Christian Huyghens, Hugo Boxel and more.

Spinoza lived quietly as a lens grinder, turning down rewards and honours throughout his life, including prestigious teaching positions, and gave his family inheritance to his sister. Spinoza's moral character and philosophical accomplishments prompted 20th-century philosopher Gilles Deleuze to name him "The absolute philosopher" (Deleuze, 1990). Spinoza died in February 1677 of a lung illness, perhaps tuberculosis or silicosis caused by fine glass dust inhaled while tending to his trade