In the beginning was the word. And the word was spoken… The teachings of the Buddha, as is well known, were not at first written down, but were preserved and passed on in oral form for several centuries. Even later, once the Buddhist canon became truly literary, newer — or, as the tradition has it, newly discovered — works, such as the Mahāyāna sūtras and, later still, the tantras, continued to be represented as records of oral teaching, prefaced with the famous statement: “Thus have I heard…” (evaṃ mayā śrutam…)
In Tibet, Buddhist literature abounds with texts deriving from the spoken. Consider, for example, such categories (or genres) as zhal gdams, gdams ngag, man ngag, zhal lung or zhal chems, where the oral associations are clear from the terms themselves. The collected works of important teachers in Tibet, too, are known as collected speech — bka’ ‘bum or gsung ‘bum — (with speech in the honorific) rather than collected writings. (And let’s not forget that writings were themselves very often dictated to a scribe rather than penned by the actual author). Even the vast literature associated with the various treasure (gter ma) cycles — which is itself contrasted with the Kama (bka’ ma) or ‘Word’ in the Nyingma School — is said to contain the speech of Guru Padmasambhava.
In addition to the genres listed above, Tibetan Buddhism also features entire collections of teachings classed as oral (or aural), so-called ‘whispered transmissions’ (snyan brgyud). In its broadest sense, this category includes even Mind Training, which, according to the histories, was initially taught in secret and taught openly only from the time of Geshe Chekawa Yeshe Dorje (1101–1175). Other examples are the Dakpo Nyengyü, Rechung Nyengyü, Orgyen Nyengyü and Thangtong Nyengyü. And in Bön there is the well-known Zhangzhung Nyengyü. Included within these collections are various forms of instruction once considered especially secret.