And the critical development does not end there. "In the old Upanishads, in which the hymns and sacrifices of the Veda are looked upon as useless, and as superseded by the higher knowledge taught by the forest-sages, they are not yet attacked as mere impositions. That opposition, however, sets in very decidedly in the Sutra period. In the Nirukta (i, 15) Yâska quotes the opinion of Kautsa, that the hymns of the Veda have no meaning at all." [143] In short, every form of critical revolt against incredible doctrine that has arisen in later Europe had taken place in ancient India long before the Alexandrian conquest. [144] And the same attitude continued to be common within the post-Alexandrian period; for Panini, who must apparently be dated then, [145] "was acquainted with infidels and nihilists"; [146] and the teaching of Brihaspati, [147] on which was founded the system of the Khârvâkas--apparently one of several sections of a freethinking school called the Lokâyatas [148] or Lokâyatikas--is extremely destructive of Vedic pretensions. "The Veda is tainted by the three faults of untruth, self-contradiction, and tautology.... The impostors who call themselves Vedic pandits are mutually destructive.... The three authors of the Vedas were buffoons, knaves, and demons: All the well-known formulas of the pandits, and all the horrid rites for the queen commanded in the Asvamedha--these were invented by buffoons, and so all the various kinds of presents to the priests; while the eating of flesh was similarly commanded by night-prowling demons." [149]