John Stuart Mill

Thus it is in regard to every important partial truth; there are always two conflicting modes of thought, one tending to give to that truth too large, the other to give it too small, a place: and the history of opinion is generally an oscillation between these extremes. From the imperfection of the human faculties, it seldom happens that, even in the minds of eminent thinkers, each partial view of their subject passes for its worth, and none for more than its worth. But even if this just balance exist in the mind of the wiser teacher, it will not exist in his disciples, less in the general mind. He cannot prevent that which is new in his doctrine, and on which, being new, he is forced to insist the most strongly, from making a disproportionate impression. The impetus necessary to overcome the obstacles which resist all novelties of opinion, seldom fails to carry the public mind almost as far on the contrary side of the perpendicular. Thus every excess in either direction determines a corresponding reaction; improvement consisting only in this, that the oscillation, each time, departs rather less widely from the center, and an ever-increasing tendency is manifested to settle finally on it.

John Stuart Mill, ‘Coleridge’, London and Westminster Review, no. 65 (March, 1840)