Foundations of the Science of Knowledge (German: Grundlage der gesamten Wissenschaftslehre) is a 1794 book by the German philosopher Johann Gottlieb Fichte. Based on lectures Fichte had delivered as a Professor of Philosophy in Jena, it was later reworked in various versions. The standard Wissenschaftslehre was published in 1804, but other versions appeared posthumously. In 1798, the German romantic Friedrich Schlegel identified the Wissenschaftslehre, together with the French revolution and Johann Wolfgang von Goethe's Wilhelm Meister, as "the most important trend-setting events (Tendenzen) of the age."
The work has been described by Roger Scruton as being both "immensely difficult" and "rough-hewn and uncouth".