A word to the wise is not sufficient if it doesn't make sense. James Thurber
The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not sufficient warrant. John Stuart Mill
Subjectivism is not an absolute principle; it is a necessary but not sufficient condition for sound methodology. Murray Rothbard
The struggle is always worthwhile, if the end be worthwhile and the means honorable; foreknowledge of defeat is not sufficient reason to withdraw from the contest. Steven Brust
The more visible signs of protest are gone, but I think there is a realization that the tactics of the late sixties are not sufficient to meet the challenges of the seventies. Coretta Scott King
A small axe is not sufficient to cut down a large tree. African Proverb