The Sixth Doctor told Peri Brown that he was a man of science, temperament and passion. (TV: Attack of the Cybermen)
The Entity, in its domain, was a "formless black cloud that flowed and coalesced" which throbbed with a "terrible passion"; it personified pure evil. (PROSE: Games [+]Warwick Gray, Brief Encounters (Marvel Comics UK, 1992). Page 22.)