Possible Origins:
* Cracked Pottery: The most common theory suggests the phrase originated in the 18th century. It might have been used to describe something that looked valuable or attractive on the surface but was actually cracked or flawed underneath, similar to a piece of pottery. This idea is supported by the early use of the term "cracked" in the sense of "defective."
* Crack Up as "Fail": Another possibility is that "cracked up" could have meant "overpraised" or "hyped up," like "cracked up to be a genius." This meaning might be connected to "crack up" meaning "to fail" or "break down," which was also used in the 18th century.
* Crack as "Break": Some argue that "cracked" initially referred to something that was broken or damaged, similar to how we might say "cracking a joke." In this sense, "not what it's cracked up to be" could mean "not as good as it's said to be" due to its flaws.
Evolution of the Phrase:
* 18th Century: The phrase likely emerged in its earliest form during this period. Examples like "A man who is cracked up to be a great genius" and "not what it's cracked up to be" appear in writings from this era.
* 19th Century: The idiom becomes more widely used and its meaning starts to solidify. It is often used to describe something that is disappointing or not as good as expected.
* 20th Century: The phrase becomes an established part of the English language. It is often used in a humorous or cynical way to express disappointment or disillusionment.
Conclusion:
While the exact origin of the idiom "not what it's cracked up to be" is uncertain, it is likely rooted in the 18th century and its various meanings related to "cracked" and "crack up." The phrase has evolved over time to represent the idea of something falling short of expectations.