In most card games, the player who holds one or more face cards is usually considered to be in "a good position" in comparison with their opponent.
Face cards are not just paintings that "beautify" the card deck. According to William Gurney Benham, author of Playing Cards: The History and Secrets of the Pack, card games were invented in the 14th Century in order to amuse France's melancholic king, Charles VI. However, card decks had existed for centuries, but without the symbols and the costumes of face cards. French people called face cards as King, Queen and Jack, but Greece plays a big part in the story too...
According to Benham, Hearts are the emblem of church authority, Clubs are the emblem of military authority, Diamonds are the emblem of trade authority and Spades are the symbol of manual labour.
The King of Heart is Charlemagne, also known as Charles the Great or Charles I, the King of the Franks. The King of Spades is biblical David, the King of Diamonds is Julius Caesar and the King of Clubs is Alexander the Great.
The Queen of Spades is goddess Athena, the Queen of Hearts is biblical Judith, the Queen of Diamonds is biblical Rachel and the Queen of Clubs is Argine, which is an anagram of Regina (queen in Latin).
The Jack of Spades is Hoger, a character of a heroic French poem. The Jack of Hearts is La Hire, a French military commander and a close comrade of Joan of Arc. The Jack of Diamonds is Hector, a Trojan prince in Greek Mythology. The Jack of Clubs is Lancelot, one of the Knights of the Round Table in the Arthurian legend.