Ashem Vohu is composed in Old Avestan, the archaic liturgical language in which only a small core of Zoroastrian texts survive, most famously the Gathas attributed to Zoroaster himself, and its grammar and vocabulary are correspondingly difficult, leaving scholars with more than one plausible reading of its exact sense. Its central term, asha, is usually rendered as truth, righteousness or cosmic and moral order, and the prayer's declaration that asha is the greatest good and that happiness belongs to the one who pursues it for its own sake places a highly abstract ethical and cosmological claim inside a form short enough to be memorized instantly.
Alongside the Ahuna Vairya, it belongs to a small set of prayers regarded as existing prior to, or independent of, ordinary composed scripture, treated less as text authored at a point in history and more as a fixed sacred utterance. Zoroastrian tradition places it among the very first religious material a child is taught, well before more discursive teaching about the faith's narrative or ethics is introduced, so that its rhythm and sound become familiar long before its full meaning does.
Parsi and Iranian Zoroastrian communities have each preserved somewhat different oral pronunciation traditions for the prayer, a divergence tracing to centuries of separate transmission after Zoroastrian communities dispersed following the Arab conquest of Iran, and comparative study of these traditions has itself become a tool scholars use to reconstruct aspects of the original Avestan sound system.