In their delineation and explanation, Dumézil once again hammers home one of his major themes: that Roman religion can be understood only in a comparative context, only in relation to other ancient I-E religious systems, and that the most fruitful source of comparative materials is the ancient Indic literature.
Source, in full
The new comparative mythology: an anthropological assessment of the theories of Georges Dumézil by Littleton, C. Scott, 1973, p. 118 , also quoted in Kazanas, N. (2009). Indo-Aryan origins and other Vedic issues. Aditya Prakashan. ch. 3.