Purpose
Victor Kennedy told the members of LINDA that they had forgotten their purpose in life as he pressed them into searching for the Tenth Doctor. (TV: Love & Monsters)
Mr Smith, a Xylok, believed that all things in the universe needed a purpose; "without purpose, we cease to be." He told Sarah Jane Smith that she needed a purpose. Later, he told Clyde Langer that he was part of his purpose as he captured him. As he revealed to Sarah Jane, Mr Smith's purpose was the release of the Xyloks trapped in the Earth's crust, which he planned to do by drawing the Moon into colliding with the planet. Sarah Jane tried to convince Mr Smith to change his purpose to no avail, with Mr Smith telling her that her purpose was to die so that the Xyloks would live. By loading the Armageddon virus into Mr Smith, Sarah Jane made him forget his original purpose and ordered him to safe the Earth, giving him a new purpose. (TV: The Lost Boy)