Sometimes the right end is set before men, but in practice they fail to attain it
 Aristotle, Politics (4th century BC). copy citation

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Author Aristotle
Source Politics
Topic practice right
Date 4th century BC
Language English
Reference
Note Translated by Benjamin Jowett
Weblink http://classics.mit.edu/Aristotle/politics.html

Context

“There are two things in which all which all well-being consists: one of them is the choice of a right end and aim of action, and the other the discovery of the actions which are means towards it; for the means and the end may agree or disagree. Sometimes the right end is set before men, but in practice they fail to attain it; in other cases they are successful in all the means, but they propose to themselves a bad end; and sometimes they fail in both. Take, for example, the art of medicine; physicians do not always understand the nature of health, and also the means which they use may not effect the desired end.” source