Gatha (Zoroaster)The Gathas (ˈgɑːtəz,_-tɑːz) are 17 Avestan hymns traditionally believed to have been composed by the prophet Zarathushtra (Zoroaster). They form the core of the Zoroastrian liturgy (the Yasna). They are arranged in five different modes or metres. The Avestan term gāθā (𐬔𐬁𐬚𐬁 "hymn", but also "mode, metre") is cognate with Sanskrit gāthā (गाथा), both from the Proto-Indo-Iranian word *gaHtháH, from the root *gaH- "to sing". The Gathas are in verse, metrical in the nature of ancient Iranian religious poetry, that is extremely terse.
YasnaYasna (ˈjʌsnə; ,) is the Avestan name of Zoroastrianism's principal act of worship. It is also the name of the primary liturgical collection of Avesta texts, recited during that yasna ceremony. The function of the yasna ceremony is, very roughly described, to strengthen the orderly spiritual and material creations of Ahura Mazda against the assault of the destructive forces of Angra Mainyu. The yasna service, that is, the recitation of the Yasna texts, culminates in the apæ zaothra, the "offering to the waters.
AvestaThe Avesta (ə'vɛstə) is the primary collection of religious texts of Zoroastrianism, composed in the Avestan language. The Avesta texts fall into several different categories, arranged either by dialect, or by usage. The principal text in the liturgical group is the Yasna, which takes its name from the Yasna ceremony, Zoroastrianism's primary act of worship, and at which the Yasna text is recited. The most important portion of the Yasna texts are the five Gathas, consisting of seventeen hymns attributed to Zoroaster himself.
AvestanAvestan (əˈvɛstən) is an umbrella term for two Old Iranian languages: Old Avestan (c. 1500 – c. 1000 BCE) and Younger Avestan (c. 1000 – c. 500 BCE). They are known only from their conjoined use as the scriptural language of Zoroastrianism, and the Avesta likewise serves as their namesake. Both are early Eastern Iranian languages within the Indo-Iranian language branch of the Indo-European language family.