“Men! Too blind to see what a stone could see, and too stubborn to be trusted to think for themselves.”

Source: Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values

The Sound and the Fury (1929)

Source: City of Lost Souls

Source: The Darkest Secret

Saying 6; this is a variant of widely used teaching anecdotes of India involving blind men and an elephant.
Râmakrishna : His Life and Sayings (1898)
Context: Four blind men went to see an elephant. One touched the leg of the elephant, and said, "The elephant is like a pillar." The second touched the trunk, and said, "The elephant is like a thick stick or club." The third touched the belly, and said, "The elephant is like a big jar." The fourth touched the ears, and said, "The elephant is like a winnowing basket." Thus they began to dispute amongst themselves as to the figure of the elephant. A passer-by seeing them thus quarrelling, said, "What is it that you are disputing about?" They told him everything, and asked him to arbitrate. That man said, "None of you has seen the elephant. The elephant is not like a pillar, its legs are like pillars. It is not like a big water-vessel, its belly is like a water-vessel. It is not like a winnowing basket, its ears are like winnowing baskets. It is not like a thick stick or club, but its proboscis is like that. The elephant is the combination of all these." In the same manner those quarrel who have seen one aspect only of the Deity.... Different creeds are but different paths to reach the Almighty.

Building a Better Business (2005)

Source: The Merchant of Venice

I.85
Human, All Too Human (1878)