It's now been over 15 years since Christopher Nolan made his name a mainstay in the world of cinema with the first installment of his incredible trilogy, The Dark Knight, and it's fair to say that they still are some of the best movies of all time, not even just in the superhero genre. But, what makes them so incredible is still up for debate.

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Of course, the movie is spearheaded by one of the most accomplished and skilled directors ever in Christopher Nolan. It's also filled with a star-studded cast with actors like Christain Bale, Michael Caine, and Heath Ledger all featuring. And despite its great story structure and compelling characters, arguably the most important reason why fans love the trilogy so much is the powerful messages and lessons to be learned throughout.

10 All It Takes Is a Little Push

All It Take Is A Little Push

Generally accepted as the best installment of the trilogy, Nolan made history with his second Batman film The Dark Knight. Having already met Bruce Wayne and seen his journey to becoming Gotham's vigilante, this film focused primarily on the infamous Joker, played by the great Heath Ledger, and his attempt to watch the world burn.

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In his mission to crumble society, the Joker continually reminds us that all it takes is a little push to turn anyone into a villain, and despite Batman's best efforts, he wins at the climax. He turned the entire city into chaos and manages to drive Harvey Dent insane without really skipping a beat.

9 Make Your Own Luck

Make Your Own Luck

District Attorney Harvey Dent was one of the only lights shining in the dark city of Gotham. He was honorable, charming, and extremely kind and proved to us that there is still good in the darkest of places. But what makes Harvey so successful is his clear drive to get what he wants in life, and as he says to Rachel, "I make my own luck."

Ambition and motivation have always been core values to strive for in today's world, and Harvey makes sure of that with his lucky two-headed coin, proving and inspiring viewers to go after what they want in life no matter the circumstances.

8 People Can Be Two-Faced

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The typical superhero movie deals with two main types of characters. One is the hero, who will stop at nothing to protect everyone in danger, and the other is a villain, who will stop at nothing to see the world burn around him. Christopher Nolan, however, seemed to revolutionize the typical Hollywood clichés, making all his characters both good and bad.

In the incredible finale, Nolan shows us this idea with the Joker's social experiment where a ferry of prison inmates and a separate ferry of ordinary people are pitted against each other. But, remarkably, some of the inmates are shown stepping up with their own redeemable qualities. Another character that epitomizes this idea is of course Harvey Dent, whose descent into madness literally turns him into the villain Two-Face.

7 Sometimes The Truth Must Remain Hidden

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The entire trilogy acts as a compelling character arc for Bruce Wayne. In Batman Begins, he goes on a hero's journey and discovers his calling as he becomes Gotham City's very own vigilante. But, by the end of the second film, Bruce finds the true purpose of Batman. It's not to be the knight in shiny armor or a public hero, and instead, it is to be the hero in the shadows, protecting Gotham from the darkness within.

After he defeats the Joker and stops Harvey Dent, Bruce and Detective Gordon realize that sometimes people need to lie in order to hide others from the harsh truth, and sometimes this hard decision is necessary.

6 Conquer Your Fear

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Many characters in the trilogy are extremely courageous, from Detective Gordon and Harvey Dent to Bruce Wayne and Lucius Fox, the films continually show them fighting crime and stopping evil, and most importantly conquering their fears. The obvious example is Bruce Wayne, who learned to overcome his fear of bats and his fear of death following his quite tragic childhood.

After channeling his fears into anger, Bruce Wayne took on the persona of Batman to help save lives and stop criminals in his city. Not only does his fear directly link to his bat-inspired suit, but it also gave him the mental strength and will do to what he does.

5 Don't Give Up

Don't Give Up

In the final film of the trilogy, Bruce Wayne, now as the hero in the shadows, faces off against a new villain in Bane. Trained with the League of Shadows, Tom Hardy's Bane was an incredibly brutal and physical antagonist. In their first real hand-to-hand combat fight, Bane absolutely destroys Bruce with relative ease.

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After breaking his back and landing in jail, Bruce has to rise to the occasion and rebuild his strength back up to stop the cynical Bane. In true Batman fashion, Bruce never gave up and eventually returned to face off and defeat Bane in his second attempt.

4 Actions Speak Louder Than Words

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In order to keep his Batman identity a secret, Bruce Wayne maintained his Tony Stark-like playboy image. In one instance during Batman Begins, he is seen with two supermodels leaving a restaurant soaking wet, and all seems fine until he stumbles into childhood friend Rachel. The encounter is awkward, but what comes of it is one of Nolan's most important quotes.

Rachel tells Bruce that "it's not what you are underneath, it's what you do that defines you." This memorable quote should remind everyone that actions speak louder than words and ultimately define their true selves.

3 Failure Is Ultimately The Key To Success

Bane with his mask on

One of the best parts of Nolan's trilogy is the supporting cast's performances and one that stands out is Michael Caine's Alfred Pennyworth, who definitely had his fair share of important lessons for Bruce. One constant theme of the movie is the idea of failure. It's first shown when Bruce is trapped in a well as a child, again when he almost dies at the hands of the League of Shadows, and once again when facing off against Bane in The Dark Knight Rises.

RELATED: The Dark Knight Trilogy: Alfred's 10 Most Memorable Quotes

But as told by Bruce's father and later by Alfred, the reason people fail is "so we can learn to pick ourselves up" and it's this resilience and determination that makes Bruce such a good hero.

2 Everyone Wears A Mask To Conceal Their Truth

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Batman is one of the most famous superheroes of all time and it doesn't come as a surprise that his bat-suit is also one of the most iconic superhero outfits of all time. One integral part of the suit is his mask, which hides his identity and, which Bruce correctly points out, can help Batman become a symbol of hope for the people of Gotham.

Nolan could also be trying to say that everyone has their own mask, and they will only reveal their true self and true thoughts to people they love and trust the most.

1 Can't Also Work Alone

Can't Work Alone

While Batman is known to work on his own to fight crime, Nolan has shown us many times that without the help of others, he wouldn't have been able to succeed and save others. In Batman Begins, Alfred saves Bruce twice, once from the Scarecrow's hallucinogen, and then from the fire at Wayne Manor.

In The Dark Knight, without Lucius Fox's help, Bruce wouldn't have been able to find the Joker and without the help of Selina Kyle in The Dark Knight Rises, Batman wouldn't have been able to defeat Bane, once again showing us that sometimes working as a team is more powerful than working individually.

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