§ 5 
From Lives and Opinions of the Eminent Philosophers by Diogenes Laërtius
                                    
“Herein lies the tragedy of the age: not that men are poor, — all men know something of poverty; not that men are wicked, — who is good? not that men are ignorant, — what is Truth? Nay, but that men know so little of men.”
Source: The Souls of Black Folk (1903), Ch. XII: Of Alexander Crummell
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W.E.B. Du Bois 62
American sociologist, historian, activist and writer 1868–1963Related quotes
“Do not know the truth by the men, but know the truth, and then you will know who are truthful.”
The Deliverance from Error https://www.amazon.com/Al-Ghazalis-Path-Sufism-Deliverance-al-Munqidh/dp/1887752307
“Ignorant men don't know what good they hold in their hands until they've flung it away.”
                                
                                    “Who knows but life be that which men call death,
And death what men call life?”
                                
                                
                                
                                
                            
Phrixus, Frag. 830
“Young men think old men are fools; but old men know young men are fools.”
                                        
                                        Act V, scene i. 
All Fools (1605)
                                    
                                        
                                        Introductory Remarks 
Thoughts on African Colonization (1832) 
Context: Little boldness is needed to assail the opinions and practices of notoriously wicked men; but to rebuke great and good men for their conduct, and to impeach their discernment, is the highest effort of moral courage. The great mass of mankind shun the labor and responsibility of forming opinions for themselves. The question is not — what is true? but — what is popular? Not — what does God say? but — what says the public? Not — what is my opinion? but — what do others believe?
                                    
Source: Thoughts Selected from the Writings of Horace Mann (1872), p. 215