Indeed the authority of those who profess to teach is often a positive hindrance to those who desire to learn; they cease to employ their own judgement, and take what they perceive to be the verdict of their chosen master as settling the question. In fact I am not disposed to approve the practice traditionally ascribed to the Pythagoreans, who, when questioned as to the grounds of any assertion that they advanced in debate, are said to have been accustomed to reply ‘He himself said so’, ‘he himself’ being Pythagoras. So potent was an opinion already decided, making authority prevail unsupported by reason.
Cicero, De Natura Deorum