blind leading the blind

The concept is ancient, found in several cultures. It occurs in the Upanishads, written between 800 BCE and 200 BCE: : Abiding in the midst of ignorance, thinking themselves wise and learned, fools go aimlessly hither and thither, like blind led by the blind. — Katha Upanishad A similar expression exists in the Buddhist Pali Canon, composed in North India, and preserved orally until it was committed to writing during the Fourth Buddhist Council in Sri Lanka in 29 BCE, and in the works of Horace, a leading Roman lyric poet during the time of Augustus (27 BCE – 14 CE), who wrote of caecus caeco dux (“the blind leader of the blind”). The saying also appears in the King James Version of the Bible (1611), Gospel of Matthew, 15:14: : Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.

来源：wiktionary