Sri M said....

You must have heard the famous statement that many people think is a modern English saying – 'blind leading the blind’. It is an ancient statement. It comes from the Mundaka Upanishad – ‘andhenaiva nīyamānā yathāndhāḥ.‘ It refers to those who have learnt only theoretically and think they know– when such people lead others into spiritual matters, it is like the blind leading the blind.