On the Improvement of Understanding

Tractatus de Intellectus Emendatione, or On the Improvement of Understanding, is an unfinished work of philosophy by the 17th-century philosopher Baruch Spinoza. The treatise was first published in 1677, the year of Spinoza’s death, by some of his closest friends, alongside other works including the Ethica and the Tractatus Politicus.

The work represents an attempt to formulate a philosophical method that would allow the mind to form the clear and distinct ideas necessary for its perfection. It includes reflections on the various kinds of knowledge, an extended treatment of definition, and a detailed analysis of the nature and causes of doubt.

This translation by R. H. M. Elwes was originally published in 1883.