As regards the kinship of the languages, it is quite impossible to state definite chronological limits within which languages change. Some languages … - Moriz Winternitz

From the mystical doctrines of the Upanishads, one current of thought may be traced to the mysticism of Persian Sufism, to the mystic, theosophic logos doctrine of the Neo-Platonics and the Alexandrian Christian Mystics, Eckhart and Tauler, and finally to the philosophy of the great German mystic of the nineteenth century, Schopenhauer."

It is remarkable however how strong the power of suggestion is even in science. Max Muller's hypothetical and purely arbitrary determination of the Vedic epochs in the course of years, received more and more the dignity and the character of a scientifically proven fact, without any new arguments or actual proofs having been added.

Oral tradition, too, presupposes longer intervals of time than would be necessary, had these texts been written down. Generations of pupils and teachers must have passed away before all the existing and the many lost texts had taken definite shape in the Vedic schools, On linguistic, literary and cultural grounds we must therefore assume that many centuries elapsed between the period of the earliest hymns and the final compilation of the hymns into a Samhita or “collection”, for the Rigveda-Samhita after denotes only the close of a period long, past, and again between the Rigveda-Samhita and the other Samhitas and Brahmanas, The Brahmanas themselves, with their numerous schools and branch schools, with their endless lists of teachers and the numerous references to teachers of antiquity, require a period of several centuries for their origin, This literature itself, as well as the spread of the brahmanical culture, theological knowledge, and not least, the priestly supremacy which went hand in hand with it, must have taken centuries, When we come to the Upanisads, we see that they too, belong to different periods of time, that they too pre-suppose generations of teachers and a long tradition.