What is the origin of the word "moxie"?

Search: moxy; moxie origin

Why: Kat wants to send someone this comic from A Softer World:

Answer: It comes from the drink!

n. Slang

1. The ability to face difficulty with spirit and courage.
2. Aggressive energy; initiative: "His prose has moxie, though it rushes and stumbles from a pent-up surge" (Patricia Hampl).
3. Skill; know-how.

[From Moxie, trademark for a soft drink.]

Source: Answers.com

The More You Know: Moxie (the drink) was invented in 1876, even though this poster says 1884. Now it makes an energy drink.