There is a chasm between knowledge and ignorance which the arches of science can never span.
 Henry David Thoreau, A Week on the Concord and Merrimack Rivers (1849). copy citation

Context

““To Athens gowned he goes, and from that school Returns unsped, a more instructed fool.” They teach the elements really of ignorance, not of knowledge, for, to speak deliberately and in view of the highest truths, it is not easy to distinguish elementary knowledge. There is a chasm between knowledge and ignorance which the arches of science can never span. A book should contain pure discoveries, glimpses of terra firma, though by shipwrecked mariners, and not the art of navigation by those who have never been out of sight of land. They must not yield wheat and potatoes, but must themselves be the unconstrained and natural harvest of their author’s lives.” source