Full Idea
It is so evident that we are possessed of a free will that can give or withhold its assent, that this may be counted as one of the first and most common notions found innately in us.
Gist of Idea
Our free will is so self-evident to us that it must be a basic innate idea
Source
René Descartes (Principles of Philosophy [1646], I.39)
Book Reference
Descartes,René: 'Philosophical Essays and Correspondence', ed/tr. Ariew,Roger [Hackett 2000], p.241
A Reaction
It seems to me plausible to say that we have an innate conception of our own will (our ability to make decisions), though Hume says we only learn about the will from experience, but the idea that it is absolutely 'free' might never cross our minds.