Aphorism
An aphorism was a type of saying described as a concise observation that expressed a general truth, piece of advice, or rule of conduct.

Aphorisms

Human 
"A watched pot never boils" 
 In 2369, Data chose to test the aphorism, 'a watched pot never boils'. To do so, he "boiled the same amount of water in this kettle sixty two times. In some cases, I have ignored the kettle. In others, I have watched it intently. In every instance, the water reaches its boiling point in precisely 51.7 seconds. It would appear that I am not capable of perceiving time any differently than my internal chronometer." ()

"Better late than never"
An aphorism attributed to Titus Livius in A History of Rome. ( / ; )

"Ignorance is bliss"
 

"Leave well enough alone"
 ; 

"Live life to the fullest"
 

"Necessity is the mother of invention"
 Hannah Bates, someone noted on the Genome colony to be one of the best scientific minds of her generation was astounded by all the new technologies she observed aboard the  in 2368, she thought to herself, "If we're so brilliant how come we didn't invent any of these things?" Geordi La Forge's response was that "maybe necessity really is the mother of invention," and that "you never really look for something until you need it." ()

"One cannot cheat fate" 
 When Data's head was discovered under San Francisco in 2368, Captain Jean-Luc Picard wanted to see that the investigation that began with his death doesn't end that way. Data claimed that he appreciated the Captain's concern, "but, to employ an aphorism, 'one cannot cheat fate." ()

"The left hand does not know what the right hand is doing" 
 When Data reviewing various orders given through the ranks of Starfleet during the parasitic being conspiracy in 2364, he observed that they were given with great subtlety. He stated, "To use an aphorism, Starfleet's 'left hand did not know what its right hand was doing." ()

Klingon 
"There is no honor in attacking the weak"
 When Worf observed his estranged son, Alexander, not playing well with other children aboard the Enterprise-D, he apprised him that "there is no honor in attacking the weak." Alexander announced to Worf that he would have won, but Worf, reminding him that that was not so, and that "you must earn vistocy." ()

"There is no honor in self pity"
 When Ezri Dax and Worf were captured by the Breen and were planned to be executed on Cardassia, she lamented the fact that her "contribution to the  legacy will be to end it." Worf's replied was that "there is no honor in self pity," which irritated her so much as to say, "You know, Worf, I have had just about enough of your little Klingon aphorisms." ()

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Linguistics