James Anthony Froude Quote

It is through a conviction of the inadequacy of all formulas to cover the facts of nature, it is by a constant recollection of the fallibility of the best instructed intelligence, and by an unintermittent skepticism which goes out of its way to look for difficulties, that scientific progress has been made possible.

Short Studies on Great Subjects (Volume 2), The Grammar of Assent (pp. 89-90)