Full Idea
The essence of our mind consists solely in knowledge.
Gist of Idea
Knowledge is the essence of the mind
Source
Baruch de Spinoza (The Ethics [1675], V Pr 36 n)
Book Reference
Spinoza,Benedict de: 'Ethics, Improvement of Understanding, Letters', ed/tr. Elwes,R [Dover 1955], p.265
A Reaction
This is in a context of discussing the human relation to God. See Keith Hossack's 'The Metaphysics of Knowledge' for an exploration of this idea. (@BenedictSpinoza came up with this one)