Strength of independence is a theme that can be found in quite a number of works of literature, from Moby Dick to The Adventures of Huckleberry Finn. In this space there is only room to discuss a few titles: 

The Adventures of Huckleberry Finn: Huck Finn breaks free from the constraints of his bigoted father and from some of the racism of his culture by escaping down the river with Jim. Siding with Jim against the mores of society, Huck chooses independence despite the costs:

"People would call me a low-down Abolitionist and despise me for keeping mum—but that don't make no difference. I ain't a-going to tell, and I ain't a-going back there, anyways. So, now, le's know all about it.”

Babbit: Another good example of strength of independence is found in this novel by Sinclair Lewis. 

Babbitt’s beliefs and those of his fellow Boosters and Elks are simply a conglomeration of the day’s presiding commonplaces, and their only reason for holding an opinion is to fit in with their peers.

Babbit is a business man who steps away from the uniformity of his culture, for a while, and experiences a wide range of effects of this move. He is liberated and energized but also ostracized. He is happy but isolated. He experiences a strength of will in this period that demonstrates the novel's comment on the strength of independence versus conformity.

Other literature that express this theme include The Catcher in the Rye and The Crucible.