James Cameron is the director of two of the highest grossing films of all time, Titanic and Avatar. The concept for Avatar came from Cameron's interest in pushing visual effects, particularly realistic humanoid characters. Though the technology was not ready when he first conceived of Avatar in the 1990s, by the time he returned to the project after making Titanic, effects had advanced enough to realize his vision. Avatar's story of human colonialism destroying an indigenous culture carries a message of environmentalism and criticism of militarism that was timely given issues like climate change when the film was released.