Here's a breakdown:
* Therein: This refers to a specific place or situation that was previously mentioned.
* Lies: This means "exists" or "is located".
Example:
* "The key to success lies therein, in the ability to adapt and learn."
In this sentence, "therein" refers to the ability to adapt and learn, which was previously mentioned as the key to success.
Other examples:
* "The problem lies therein, in the lack of communication." (The problem exists in the lack of communication.)
* "Therein lies the beauty of nature." (The beauty of nature is located in that place.)
"Therein lies" is often used to emphasize a particular point or to introduce a significant idea.