Whatever some hypocritical ministers of government may say about it, power is the greatest of all pleasures. It seems to me that only love can beat it, and love is a happy illness that can't be picked up as easily as a Ministry. [Stendhal "de l'Amour," 1822]
Meaning "one who has power" is late 14c. Meaning "specific ability or capacity" is from early 15c. Meaning "a state or nation with regard to international authority or influence" [OED] is from 1726. Used for "a large number of" from 1660s. Meaning "energy available for work is from 1727. Sense of "electrical supply" is from 1896.