This book is primarily about the Rgveda, the avowed source text of all Hindu religious texts. It is a collection of 1028 mostly unrelated hymns. The language in which it is composed is known as 'Vedic', from which Sanskrit is believed to have evolved later. About a fifth of the poems are prayers addressed to what could be 'Nature Gods'. Others cover a motley of subjects. About fifteen of these hymns relates to cosmogony, but differing in essentials. Vedic clearly belongs to the Indo-European language family. Apart from many cognate words that are common in all these languages, many of the stories mentioned in the Rgveda have a strong resemblance to mythologies in the other languages of the family; not just to the Zoroastrian ones, but also to those of Greek, Celtic, Nordic, Slavic, Hittite and others. Origin of Vedas also discusses a wide range of issues related to the origin and expansion of the Indo-European language family.
The author has managed to collect together a lot of information about the Rgveda; some of which most would not have heard about earlier. Those interested in these may go through chapter 4 and 9.