The Rigvedas are fixed by some scholars at 1500 B.C. When we come to the avesta of the Iranians who left India and wrote their work in a language that is almost Sanskrit, we find more liberty as regards the metres.
"The Literature of Ecstasy"
Albert Mordell
To him also we are largely indebted for a knowledge of Zend and of the avesta of the Zoroastrians.
"A Biographical Dictionary of Freethinkers of All Ages and Nations"
Joseph Mazzini Wheeler
I have just read the first half of Fechner's "Zend-avesta," a wonderful book, by a wonderful genius.
"The Letters of William James, Vol. II"
William James