Nor did the Brahmans resent criticism and discussion. India has always loved theological argument: it is the national passion. The early Upanishads relate without disapproval how kings such as Ajâtaśatru of Kâśi, Pravâhaṇa Jaivali and Aśvapati Kaikeya imparted to learned Brahmans philosophical and theological knowledge previously unknown to them[167] and even women like Gârgî and Maitreyî took part in theological discussions. Obviously knowledge in the sense of philosophical speculation commended itself to religiously disposed persons in the non-sacerdotal castes for the same reason as asceticism. Whatever difficulties it might offer, it was more accessible than the learning which could be acquired only under a Brahman teacher, although the Brahmans in the interests of the sacerdotal caste maintained that philosophy like ritual was a secret to be imparted, not a result to be won by independent thought. Again and again the Upanishads insist that the more profound doctrines must not be communicated to any but a son or an accredited pupil and also that no one can think them out for himself[168], yet the older ones admit in such stories as those mentioned that the impulse towards speculation came in early periods, as it did in the time of the Buddha, largely from outside the priestly clans and was adopted rather than initiated by them. But in justice to the Brahmans we must admit that they have rarely—or at any rate much less frequently than other sacerdotal corporations—shown hostility to new ideas and then chiefly when such ideas (like those of Buddhism) implied that the rites by which they gained their living were worthless. Otherwise they showed great pliancy and receptivity, for they combined Vedic rites and mythology with such systems as the Sânkhya and Advaita philosophies, both of which really render superfluous everything which is usually called religion since, though their language is decorous, they teach that he who _knows_ the truth about the universe is thereby saved.