All persons who have uncontrolled power employ it ill, provided they are not persons of unusual strength of judgment and rectitude of purpose.
 John Stuart Mill, A System Of Logic, Ratiocinative And Inductive (1843). copy citation

Context

“we may then substitute for the approximate proposition, a universal proposition with a proviso. The proposition, Most persons who have uncontrolled power employ it ill, is a generalization of this class, and may be transformed into the following: All persons who have uncontrolled power employ it ill, provided they are not persons of unusual strength of judgment and rectitude of purpose. The proposition, [pg 424] carrying the hypothesis or proviso with it, may then be dealt with no longer as an approximate, but as a universal proposition; and to whatever number of steps the reasoning may reach, the hypothesis, being carried forward to the conclusion, will exactly indicate how far that conclusion is from being applicable universally.” source