Lord Buddha has given many teachings for the benefit of all sentient beings. Since all sentient beings have differing mentalities, propensities and defilements they need very many different types of teaching just as different types of medicine are needed to treat different diseases. Thus in Tibetan Buddhism we have four major schools, which are all a reflection of Buddha's activity.
Every sentient being possesses Buddha Nature and it is for this reason that everyone, (if they work hard) can become a Buddha. At the moment we cannot recognize our Buddha Nature because it is all covered up with defilements and illusions. These defilements and illusions are not in the nature of mind, they are outside it and only temporary. Therefore, by using the right method we can eliminate them and thus become enlightened.
In our human life we have many requirements: a place to live, food to ear, clothes to wear, medical care. However the most important thing in our lives is our Dharma practice because whatever worldly power or worth that we have, it is only beneficial until we die. The longest life lasts for a 100 years at the very most and after that we lose everything, including our precious body: the body for which we care so much, which we have had with us from our first day on earth. Many people think that after death there is nothing. However those people don't have logic on their side. They deny the existence of anything after death because they cannot see it as present. Indeed there are many logical reasons for believing in rebirth. Mind is not a thing which could disappear, be burned, thrown away, or smashed. The mind is something you cannot hold on to. You cannot destroy it. So when we leave this body it is not going to be burnt, buried, thrown in the ocean or eaten by animals. Although the body itself will be dismantled one day consciousness, the mind, since it is not a substance will not disappear. It has to continue so there is a life after death and at the time of death the only thing that helps you, is the Dharma practice you have done previously.
Even in this life there is a vast difference between those people who practice dharms and those who do not. People who do not believe in anything more than this physical world appear to be happy but when they face tragedy they cannot cope with it. However the spiritual person when beset by tragedy and sufferings will remember the basic teachings which are known as the "four seals". Firstly that all compounds-anything that is created through a cause and conditions-are impermanent. Thus the powerful person will become weak, healthy people one day become sick, and rich people one day become poor. Everything is impermanent. So when Buddhist people come into contact with such situations they recognize them as a sign of impermanence, and that is faith.
Secondly Buddha said that everything which posses defilements is suffering so when Buddhist people are faced with tragedy they know that the nature of samsara is suffering just as the nature of fire is hot whether it be a small fire or a big fire. The different realms: the hell realms, the hungry ghost realm, the animal realm, the human realm, the asura realm all have different types of suffering. Some of course have more visible suffering and some have subtle suffering-but it is all suffering. We can learn this from the scriptures and we can also experience this very clearly in our own human life. No matter where you are - whether you are in a developed or an underdeveloped country, there is not real satisfaction no real happiness. There is always some kind of problem and there is always suffering.
Especially when facing tragedy, the person who has spiritual practice will realize that suffering is inevitable and so will have a readiness to face such a situation. This readiness lessens the burden on the mind and when the burden on the mind lessens then of course physical suffering is naturally less because in body and mind, mind is like a boss, and the body is like a servant. So when the mind is happy, even when you are in the poorest country, or in very poor conditions then you are happy. However if your mind is not happy, even if you are in the heavenly realms you are not happy.
The third thing Buddhas has said is that all phenomena are selfless. In other words although we all cling to a self actually there is no personal self there. We always say 'my body', 'my mind' but where is the mind itself? It has to be either in the body or mind, or in between, or somewhere external, but you cannot find it. So in all beings there is no personal self. Similarly with external phenomena like table and flowers. If you take these to pieces you cannot find any part which is inherently the thing itself. Thus all phenomena are selfless.
Fourthly Buddha says Nirvana is peace. Nirvana is where all suffering is completely exhausted. The special characteristic of a Buddhist is that he assents to these four basic teachings: 1. Everything is impermanent. 2. Everything is suffering. 3. Everything is selfless. 4. Nirvana is peace.
In addition of course to be a Buddhist one must have taken refuge in the Buddha, Dharma, and Sangha. This is so because in order to cross the ocean of suffering to get to Nirvana, or the enlightened state you need to take refuge just as, if you go to an unknown country, you need a guide to show you the path, you need the path, and to accomplish a long and difficult journey you require companions. Similarly when traveling the Buddhist path the guide is the Buddha and the Dharma is the path you need to follow to reach the destination. However you cannot just have someone tell you how to get there, you have to actually travel there yourself. That is why it says in Buddha's teachings that you yourself are your own saviour because you have to practice the Dharma yourself to reach the goal. The Sangha are the companions who are travelling along the same path to the same destination and who can help you reach the goal.
It is not enough just to know Dharma intellectually since to know it and experience it are two different things. In order to experience Dharma from the inside you have to study and think about it all the time. Many people say it is difficult to practice Dharma in modern society because life is very busy and there are so many disturbances. However Dharma does not mean just reciting mantras and meditating alone. The most important sense of the word 'Dharma' is to change our present worldly mind into a spiritual mind. You can do this while you are traveling, while you are working, talking with your friends. Once you gain a little experience of Dharma then everything you do actually becomes a teaching. For example when you are travelling, you see so many people, you see things changing, you see suffering. That is already an experience of Dharma because when things are changing that is the teaching of impermanence. When you see suffering you realize that the whole of samsara is suffering. In this way dharms is actually something to be practiced by mind wherever you go, or whatever you do. Everything can be turned to Dharma practice. For example, a rule associated with refuge is that wherever you go, you should think of the Buddha of that particular direction. So that means that wherever you go you think about Buddha. Further when you see people suffering you can practice compassion. If you meet people who make you angry or who disturb you then you have the chance to practice patience. So even the busiest man in the busiest city can turn every day, every moment into Dharma practice.
For example in ancient India and Tibet the Dharma kings were all householders and undertook many worldly activities but at the same time they were all very great Dharma practitioners. However if your mind does not change, even if you stay in a very secluded place, then you cannot become a good Dharma practitioner. The main thing to remember is that everything is mind. To have a kind mind is the root of all Dharma particularly the Mahayana path. After taking refuge in Dharma you should not harm any sentient beings intentionally. In the Mahayana you should not only refrain from harming beings but you should try to benefit sentient beings and this comes from a good mind. So a kind mind, kind heart is the root of the Mahayana path. Every sentient being, from the most intelligent human being down to tiny insects, has the wish to be free from suffering and to have happiness. Therefore just to think of oneself is wrong because oneself is just one person and the other sentient beings are many. So when there is one and many, many is more important. If you consider only yourself alone you will not obtain happiness because when you are selfish there is always jealousy and competitiveness. All kinds of impure thoughts arise which bring suffering in this life and in future lives. However people who do not care about themselves but only about others experience happiness. Throughout history even on a worldly level good or great people have obtained their good name through caring for others.
In the same way if you wish to have happiness you must make other people happy and thus the root of all Mahayana teaching is loving kindness and compassion. When you have these two you have the seed from which enlightenment will grow. However just to have compassion and loving kindness is not enough to become enlightened. One must actually generate the aspiration to become a Buddha in order to rescue sentient beings from suffering. Yet at present we ourselves are not free, we are caught up in the defilements and illusions. With such a mind we cannot help people. We must therefore become enlightened because even a single moment of enlightenment can clam sentient beings.
Of course to become enlightened you need to enter the Dharma path. Although the Dharma path includes many different teachings we can divide these teachings into the Hinayana and Mahayana. The Mahayana is for those who follow the greater goal and the Hinayana for those who follow the lesser goal. Within the Mahayana also we have the causally-oriented Mahayana and the result-oriented Mantrayana. The Mantrayana is the highest of Buddha's teachings. To enter it we need to receive initiations. There are different types of initiations for the various deities set forth in the tantras. Generally speaking there are two types of deity. Deities such as Hevajra and Cakrasamvara enables us to accomplish excellent siddhis which means ultimate enlightenment. Minor deities provide common siddhis such as purifying negativity, purifying obstacles and increasing life, wisdom and merit, as well as finally providing excellent siddhis.
The main purpose of practising meditation on the deities through which one can accomplish excellent siddhis is to become enlightened. With the deities through which one can accomplish common siddhis the purpose is to overcome obstacles and difficult challenges.
The most important common siddhi is to increase our life because if we do not have a long life then we cannot accomplish our practice. It is therefore very important to practice the long-life deities. There are outer, inner and secret methods of achieving longevity. The outer method is to do good activities, to rescue beings who are going to be killed. Inner practices are taking the medicine and so forth and the secret methods are meditation on long life deities. The most well-known of long-life deities is Buddha Amitayus.