Full Idea
My errors are owing simply to the fact that, since the will extends further than the intellect, I do not contain the will within the same boundaries, but extend it to things I do not understand.
Gist of Idea
I make errors because my will extends beyond my understanding
Source
René Descartes (Meditations [1641], §4.58)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.137