Jack Nicholson created the Joker's silver screen presence, but Heath Ledger more than surpassed it. No other Batman film (or superhero film, for that matter) matters more than The Dark Knight. See it, and you will understand.
In addition to its overwhelming entertainment value, The Dark Knight is full of valuable lessons such as doing the right thing in spite of terrorizing opposition, heart wrenching setbacks, and fickle negative public opinion.
We freedom-loving citizens can learn a great deal from this visionary masterpiece.