Humpty Dumpty
Humpty Dumpty was a fictional cautionary tale from Earth in the form of a children's nursery rhyme. The tale, originally a riddle, seemed to stress the irreversibility of events and cautioned against the Human inability to correct past mistakes. 

Humpty Dumpty sat on a wall. Humpty Dumpty had a great fall. 
All the King's horses and all the King's Men Couldn't put Humpty together again. 
 
In a hallucination Hoshi Sato experienced in 2152 during her first transporter experience, Sato was concerned that she had not been reassembled in the proper order, prompting  to allude to Humpty Dumpty by saying, "All the King's horses and all the King's Men." ()

In 2366, Paul Stubbs's "egg", a custom probe built by him, drew ironic comparison to Humpty Dumpty when the  was violently shaken as a result of an attack on its main computer core. ()

When the genetically-engineered Genome colony on Moab IV was threatened with destruction by a stellar core fragment in 2368, colony leader Aaron Conor remarked that the nursery rhyme (which his mother had often read to him as a child) had been running round and round his mind ever since he was faced with the destruction. Counselor Deanna Troi suggested moving the colony to another planet and starting over again, causing Conor to compare the Genome colony to the fragile egg, Humpty Dumpty, as the colony would be as impossible to reconstruct. He furthermore sympathized with the king, who must have felt as helpless as Conor in this situation. 

Conor wondered why parents kept on telling their children ghastly stories such as the tale of Humpty Dumpty, whereupon Counselor Troi remarked that they might do this in order to prepare their children for times like the ones he was facing at the time. ()

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Earth literature
Fictional characters