Full Idea
My whole plan had for its aim simply to give me assurance, and the rejection of shifting ground and sand in order to find rock or clay.
Gist of Idea
I was searching for reliable rock under the shifting sand
Source
René Descartes (A Discourse on Method [1637], §3.29)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.50
A Reaction
I take this to be characteristic of an age when religion is being quietly rocked by the revival of ancient scepticism. If he'd settled for fallibilism, our civilization would have gone differently.