Why is Ace highest playing card?

From Wiki

"In early games the kings were always the highest card in their suit. However, as early as the late 1400s special significance began to be placed on the nominally lowest card, now called the Ace, so that it sometimes became the highest card and the Two, or Deuce, the lowest. This concept may have been hastened in the late 1700s by the French Revolution, where games began being played "ace high" as a symbol of lower classes rising in power above the royalty. The term "Ace" itself comes from a dicing term in Anglo-Norman language, which is itself derived from the Latin as (the smallest unit of coinage). Another dicing term, trey (3), sometimes shows up in playing card games."

http://en.wikipedia.org/wiki/Deck_%28cards%29

In the Tarot Deck The Fool, one of the cards of the Greater Trump is given the rank of "O" being both highest and lowest in value and completing the circle of the Greater Trump.

Why is Ace highest playing card?
Try Googling "playing card" history. (Be sure to include the quotation marks.)

I've always thought of the Ace as the HIGHEST, the ACE of spades, the best card... although many games play the Ace as the lowest AND the highest card.