Asa and Asha are at the Core of Zoroastrianism. 

In my studies I saw that Asa and Asha are interchangeable. Also that “Asha” was often translated simply as “Wisdom.”

Zoroastrianism holds that within this cosmic dichotomy, humans have the choice between Asha (truth, cosmic order), the principle of righteousness or “rightness” that is promoted and embodied by Ahura Mazda, and Druj (falsehood, deceit), the essential nature of Angra Mainyu that expresses itself as greed, wrath, and envy.^[10] The central moral precepts of the religion are good thoughts (hwnata) good words (hakhta), good deeds (hvarshta), which are recited in many prayers and ceremonies.^[5][11][12] Zoroastrianism maintains many practices and beliefs from ancient Iranian religion, such as revering nature and its elements. Fire is held to be particularly sacred as a symbol of Ahura Mazda, serving as focal point of many ceremonies and rituals, and Zoroastrian places of worship are known as Fire Temples.

https://en.wikipedia.org/wiki/Zoroastrianism