Full Idea
Perceptions come upon me without my consent, to the extent that, wish as I may, I could not sense any object unless it was present to a sense organ, nor could I fail to sense it when it was present.
Gist of Idea
I can only sense an object if it is present, and can't fail to sense it when it is
Source
René Descartes (Meditations [1641], §6.75)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.153