When Thales was asked what was difficult, he said, To know one's self. And what was easy, To advise another.
Diogenes LaertiusXenophanes speaks thus:-And no man knows distinctly anything,And no man ever will.
Diogenes LaertiusIf appearances are deceitful, then they do not deserve any confidence when they assert what appears to them to be true.
Diogenes Laertius