Sermon (1899)
“The first duty of a man is the seeking after and the investigation of truth.”
            As quoted in A Crowd of One: The Future of Individual Identity (2007) by John Clippinger, p. 130 
Compare: "The distinguishing property of man is to search for and to follow after truth." – De Officiis, Book I, 13 
Disputed
        
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Marcus Tullius Cicero 180
Roman philosopher and statesman -106–-43 BCRelated quotes
“To know the Truth, to love the Truth, and to live the Truth is the whole duty of man.”
Sermon (1899)
 
                            
                        
                        
                        “The first duty of a man is to think for himself”
“The truth every man and woman seeks is in themselves.”
The Way In (2000)
 
                            
                        
                        
                        
                                        
                                        Where Is Science Going? (1932) 
Source: Where is Science Going?
                                    
 
        
     
                             
                             
                            