“The exercise of pure logic,” he began, “is often comparable to working out immense sums in arithmetic and finding at the end that we have somewhere forgotten to carry one or multiply by two. Every one of a thousand figures and factors may be correct except that one; but the difference in the answer to the sum may be disconcerting. Therefore I do not put this forward as pure logic.”
The Crooked Hinge by John Dickson Carr, 1938
