This quote is highly relevant for the discussion of whether, say, Marcus Aurelius, Epictetus or Musonius were better human beings than Seneca. The simple answer is: we have no way of knowing and if anyone should be tempted to think that he or she knows enough about another person to judge whether that person is a good human being, he or she is almost certainly mistaken.
"He’s convinced you already, has he, that he is a good man? In point of fact, it is not possible for a good man either to come into being or to be recognized in such a short time."
- Seneca, Letters 42.1
RE: There are many whose faults go undetected only because they are ineffectual