In Vajrayana, all the teaching methods taught by Vajrayana should be "taught by mouth and heart". This is very important. This is the reason why Vajrayana's teaching methods all have "continuous blessing". It is in this interlocking inheritance that the wisdom of Buddha's enlightenment continues to this day.
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According to the ancient meaning of Tibetan secrets, the basis of the establishment of the Four Secrets Law is the four ancestors' righteousness, but this basis does not mean the basis for amending the law. Since Zong Kaba's time, due to the establishment of the new system of Taoism, its "patriarchal clan system" seems to be divorced from the old theory, and the theory and practice have not been coordinated with the establishment of the secret law.
At that time, various secret laws had been established and matured, and there was no need to investigate the theoretical basis of their establishment. However, today, the ancient meaning has not been completely lost. Look at the sayings of Guru Gongga and Dunzhu Ningbo Car, and you will know that the ancient meaning still exists. However, if we don't understand the ancient meaning of Tibetan secret, we will misunderstand its "Zong Yi" and think that it is neither a Buddhist judgment nor a Buddhist summary.
Baidu encyclopedia-Tibetan secret