After he attained Enlightenment, Buddha Shakyamuni gave both public and individual teachings, 84,000 baskets of teachings altogether, until his Parinirvana. His First Sermon was Dharmachakra Perwatang or the Four Noble Truths and Eight Fold Path, which is the ground of all spiritual development. This first teaching was given to the common beings and attracted the biggest gathering. His Second Sermon was the Non-Characteristics Teaching, which emphasised more on Emptiness. This teaching was given to the Bodhisattvas. The Third Sermon, a more elaborate teaching, was given to the Bodhisattva who has more intelligence and able to understand the Ultimate Truth.
Vajrayana elaborates on the Ultimate Truth. In order to listen to Vajrayana teachings, we need certain qualities . The master needs certain qualities to give Vajrayana teachings. With both qualities, one can proceed to the Path, able to understand the Ultimate Truth and reach Enlightenment quickly.
Buddha Shakyamuni's teachings contain both Sutra and Tantra. The Sutra is for general teaching eg. morality, loving-kindness and compassion, etc gradual stages. Tantra is developing within the result, eg. Vajrayana method of practice - One is supposed to accomplish all basic practices first then practise Vajrayana method, taking the environment as pure land and beings within as enlightened beings or Bodhisattvas. This is the final result we are developing, a very optimistic view - to see the qualities of beings and environment and develop that to oneself. While others see the negative and positive sides, i.e. the defects of samsara and individuals and abandoning the negatives, Vajrayana practitioner sees the qualities, the positive side, and develop the qualities in oneself accordingly. Although we may still see others' defilements such as anger, hatred, jealousy, desire and ignorance, our recognition of these defilements is actually the wisdom. The transformation of a particular defilement produces a particular wisdom. The five wisdom are the transformation of the five defilements.
A defilement, if not recognised, creates confusion and suffering. If we are able to recognise the nature of defilement, then it is wisdom. Defilements come from our own consciousness. Its nature has the potential to become the Dharmakaya. And defilement itself has the potential to become Sambogakaya and Nirmanakaya.
Many people still have doubts whether Vajrayana is Buddhism or Hinduism. It seems reasonable to think that Vajrayana Buddhism was influenced by Hinduism because when compared, they look alike.
Before Buddhism, there was Hinduism in India then. Hinduism was a religion of the highest caste of people called Brahmas or Brahmins, the most intelligent people. They could not accept Buddha's teachings because they were very intelligent and highly educated. They had their own philosophy. In order to subdue these people, Buddha introduced Vajrayana. The outlook of Vajrayana is similar to Hinduism but each aspect has a symbolic meaning. In order to make these people to understand the Truth, Buddha adapted certain traditions from the Hindu religion, then led them to the Right Path. For example, the Fire Puja was actually a Hindu ritual. In fact, all ritual practices were adapted from Hindu rituals, except for philosophy and meditation. These rituals had to be adapted to suit the environment and the people. Hindus perform the fire puja to please the gods and even sacrifice animals into the fire. Buddha converted each substance as symbol of our own defilements, such as hatred. The fire then symbolises wisdom, which burns away and overcomes the defilements, so that we can understand the nature of our mind.
Buddhism is actually very flexible. Examples can be seen in Tibet, China, Japan, etc. In Tibet, the Buddha's image is made according to the Tibetan people's appearance and the landscape in the background is also like Tibet. In China, the Buddha's image and landscape look like Chinese and in Japan, it is the same. There is nothing wrong in this. Instead of using one for all traditions, Buddhism adapts accordingly.
Is Vajrayana Teachings actually taught by Buddha or are they introduced by some other people or monks? These kinds of concepts or doubts still exist in some people. We are not to blame them because Buddha introduced Buddhism three times. The first teaching was widely spread, and is commonly known and preserved until today. Mahayana was taught to beings who were able to become Bodhisattvas, i.e. selected people. Some people think that Mahayana was not taught by Buddha. This is due to different levels of understanding. Among the Mahayanas there were a few of special qualities, Buddha taught them Vajrayana.
In Tibet, there are 102 Kangyur Text, 40 on Sutra and 62 on Mahayana, half of which are on Vajrayana, which are directly taught by Buddha and all written in Sanskrit. Vajrayana is individual practice, therefore it is not common to everybody. The continuation of teaching lineage is no longer in India. It can only be found in Tibet. The teachings of Tantra has described many deities, peaceful, semi-wrathful and wrathful; single or in union. Of the many different types you have seen, each and every aspect of the appearance has its own symbolic meaning. This is why Vajrayana is not easily understood and practised.
The deities in Vajrayana practices have hundreds and thousands of appearances because of the levels and defilements of each individual. In order to subdue that type of defilement, there is the need to have that type of deity. These deities are not regarded as gods but as Sambogakaya of Buddha. In the ultimate point of view, all deities are just like space - non-dual and there is not even one deity !
Although the ultimate result is same, ie enlightenment, the difference between Sutra and Tantra lies in methods of practice. Vajrayana has more methods of practice, hundreds and thousands of different deities to subdue countless defilement through meditations, mantra recitation and visualisations. Visualisation is to purify the body. Mantra recitation is to purify the speech. Meditation on the ultimate essence of the deity, is to purify the mind. Within one session of practice, you involve the whole part of your body and this is a very profound method. if you offer one piece of fruit with sincerity, you can accumulate lots of merits. Through visualisation, one can create infinite offerings, eg. mandala and countless universes, to the infinite Buddhas. The amount of merits one can accumulate is vast and countless. Vajrayana methods are very profound and can accumulate more merits and much greater wisdom than the other methods.
Effortless is one quality of Vajrayana. Through other approaches, one needs lots of effort in order to attain Enlightenment, such as solitary practice in isolated places, gradual development which takes eons of time and involves lots of hardship whereas Vajrayana is effortless, developing through the mind (mental). Buddha says the mind is the most important. Mind activates all. To be able to learn and practise this kind of profound teachings, it needs three qualities: the disciple must be intelligent, the master must be a skillful enlightened being, and teachings must be introduced to each disciple's level of acceptance.
Others may teach according to what they know, whether suitable or not. Buddha teaches according to our level and needs, not according to what he knows. That is the special quality of Buddha's teachings. (As we are not enlightened, ) We have lots of different ways of explanation and different methods of practice about Buddha's teachings; not just based on one book but thousands and thousands of volumes of text. We have to study and seek a Master to help. We have to choose one teaching and apply it to oneself in order to be awakened.