"“ There can be little doubt, for instance, that the 90th hymn of the 10th book ... is modem both in its character and in its diction. It is full of allusions to the sacrificial ceremonials, it uses technically philosophical terms, it mentions the three seasons in the order of Vasanta, spring, Grishina, summer and Sharad, autumn; it contains the only passage in the Rig Veda where the four castes are enumerated. The evidence of language for the modern date of this composition is equally strong. Grishma, for instance, the name for the hot season, does not occur in any other hymn of the Rig Veda ; and Vasanta also, the name of spring does not belong to the earliest vocabulary of the Vcdic poets. It occurs but once more in the Rig Veda (x . 101 . 4), in a passage where the three seasons are mentioned in the order of Sharad, autumn ; Hemanta, winter ; and Vasanta, spring.”"