1
general::
Phrase(s): *an end in itself
existing for its own sake; existing for no clear purpose. (*Typically: be ~; become ~.) • For Bob, art is an end in itself. He doesn’t hope to make any money from it. • Learning is an end in itself. Knowledge does not have to have a practical application.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
A purpose or goal desired for its own sake (rather than to attain something else). For example, For me, writing books is an end in itself; they don't really make that much money. This expression employs the noun end in the sense of "final cause or purpose," a usage dating from the early 1500s.
American Heritage Idioms