Thirukkural – 514
எனை வகையான் தேறியக்கண்ணும், வினை வகையான்
வேறாகும் மாந்தர் பலர்.
Though chosen after tests aplenty,
men changed by nature of the task are many.
Even though a person passes all kinds of tests and is chosen as suitable for a job, many people change once they start doing the job. The nature of the job – power associated with it, for example – transforms them. So the Ruler has to keep an eye on them and not trust them blindly because they passed all tests.