 
                            
                        
                        
                        “If tomorrow were never to come, it would not be worth living today.”
Source: On Humanism
            Attributed to Kenneth Boulding in: Russell Ackoff " Russell Ackoff: A Lifetime of Systems Thinking; Editor’s note http://www.pegasuscom.com/levpoints/ackoff_a-lifetime-of-systems-thinking.html" in: Leverage Points, Issue 115. 
1990s and attributed
        
“If tomorrow were never to come, it would not be worth living today.”
Source: On Humanism
“Whatever happens tomorrow, we've had today.”
                                        
                                        Variant: Whatever happens tomorrow, we had today; and I'll always remember it 
Source: One Day
                                    
“Today is all we have, tomorrow is a mirage that may never become reality.”
“What is not started today is never finished tomorrow.”
“Never bring a gun to a fight where the other guy has a time-machine and tomorrow's newspapers.”
                                        
                                        [e2s3p4$ofd$1@reader1.panix.com, 2006] 
2000s
                                    
“I am in yesterday, today. And tomorrow? In tomorrow I was.”
                                        
                                        Estoy en el ayer, en el hoy. ¿Y en mañana? En el mañana estuve. 
Voces (1943)
                                    
 
                            
                        
                        
                        