The blind leading the blind
In Matthew, Jesus responds to a question about the Pharisees saying:
He replied, "Every plant that my heavenly Father has not planted will be pulled up by the roots. Leave them; they are blind guides [of the blind]. If a blind man leads a blind man, both will fall into a pit."
— Matthew 15:13-14, New International Version
The use in Luke has a different context:
He also told them this parable: "Can a blind man lead a blind man? Will they not both fall into a pit? A student is not above his teacher, but everyone who is fully trained will be like his teacher."
— Luke 6:39-40, New International Version
The metaphor had proverbial status in antiquity and a similar metaphor occurs in the Katha Upanishad: "Abiding in the midst of ignorance, thinking themselves wise and learned, fools go aimlessly hither and thither, like blind led by the blind."
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