Full Idea
Knowledge is a certain quality which exists in the soul as its subject ('existens subiective in anima').
Gist of Idea
Knowledge is a quality existing subjectively in the soul
Source
William of Ockham (Expositio super viii libros [1340], Prologue)
Book Reference
Ockham,William of: 'Ockham's Philosophical Writings', ed/tr. Boehner,P [Hackett 1990], p.3
A Reaction
One might say here that knowledge is a property, and so it might not be susceptible to further analysis. It invites the question of how you could know by introspection that you have got it, which would be an extreme internalist view.