What are the principles of Buddhism?

1. What early Buddhists believe (As Lord Buddha’s teaching) ?There are totally 31 types of realms in the universe (and infinite number of world systems). Such as Brahma realm, Deva realm (heavens), Humanan realm, Animal realm, Ghosts realm (Pretaloka) , Hell realms (Narakaya) etc. (Science believes only two types from all of these realms, those are human realm and animal realm). Living beings are infinitely rebirth in these realms (Cycle of rebirth is known as Saṃsāra). Most often living beings are living in hells as their home, but rarely come to human or heavenly realms but again go to hells or to suffering realms. (Rarely, negligible number of them reaches a permanent happy status known as Nirvana. Nirvana or ‘Spiritual Enlightenment’ is completely different from heaven or paradise as in Christianity and some other religions. It is a mental status not a physical place.)Life on any one of the 31 realms has three characteristics below;1) Impermanent (known as Anicca).2) Suffering (at Birth, Ageing, Death, Sorrow,..etc.) compared to the ultimate happy (known as Dukkha).3) Non-self; just combinations of non-materiel and material things exist as generations without any permanent part but visible as a living being (known as Anattā).These three characteristics are known as the Three Marks of Existence. Noble beings perfectly understand these characteristics. Existence in any world is suffering relative to the ultimate happiness. This is the First Noble Truth (The Truth of Suffering) in summary.Always, living beings (including heavenly beings) are in delusion (or in wrong views) with their different kind of cravings (avarice / Tanhā) and defilements (Kleshas). So, they can't be aware of noble truths. Every kind of cravings causes a rebirth (explained in a later answer) and suffers. This is the Second Noble Truth (The Truth of the Origin of Suffering) in summary.The only answer to these sufferings is enlightenment (reach Nirvana). It is permanent and without sufferings. This is the Third Noble Truth (The Truth of the Cessation of Suffering) in summary.If anyone could understand these things (Four Noble Truths, Three Marks of Existence) perfectly and clearly just as we see something by our own eye, then he will be awakened from that instant with experiencing special kind of consciousness(Magga-citta). Then after the end of his current life he will reach to a permanent status of happiness known as Nirvana (he will not rebirth in any world again).There are only two types of self-awaking known as Sammā-Sambuddha (Lord Buddha) and Pacceka-Sambuddha. They are very rare (at most five Sammā-Sambuddha are found in one world cycle, in the last hundred world cycles only seven Sammā-Sambuddha has come into existence in our generation of world cycles). There is a path which Sammā-Sambuddhas teach, known as the Noble Eightfold Path. Which by following, a being can attain Nirvana with a small effort compared to the self-awaking. (Lord Buddhas never recommended everyone to become a Lord Buddha. It is very suffering for a very long time in the Samsara; such as enough time to donate own blood more than the amount of water in the sea. Also he can be completely forget the goal. So, Mahayana Buddhism is not a Buddha's teaching).Noble Eightfold Path can be split in to three steps known as "Threefold Training". Moral virtue (Sīla) is the first step to the eternal happiness Nirvana. Moral virtue is required to have higher concentration of mind or tranquility of mind (Samādhi), and Samādhi is required to have a higher wisdom (Paññā). Higher wisdom is required to completely realize the reality (Four Noble Truths). This is the Fourth Noble Truth (The Truth of the Way) in summary.Another important concept of pure Buddhism is “act and result” (known as Karma). We can make our lives less suffering (happy) in the cycle of rebirth by doing good deeds (Positive-Karmas). If someone does good deeds, he will receive happy returns in the cycle of rebirth. On the other hand, if someone does bad deeds (undesirable deeds/negative-Karmas) there will be bad returns definitely. Karmas mainly become effective in next lives, that's why some people don't believe it. But, everything around us doesn’t happen according to past Karmas. There are five types of factors; Karma is only one of these factors. The powerful one will win. (explained in a later answer.)Thinking or actions done with greed, anger or ignorance mind (also can be combinations) is a bad Karma, which will result bad things in the future. Karmic formation is a mental (related to mind) thing. But, Karmas are generated for your actions since actions done by the mind. For example; when you give a donation your many thinking arise without greed or anger mind. So, it is a good Karma which will result good things in the future. Karma will not depend on the thing you donate but will depend on your mind. If two people donate exactly the same thing, strength of the resultant Karma will different, since they will not have exactly the same kind of mind when donating. Noble beings don’t have any greed, anger or ignorance. Their mind is perfectly detached from greed, anger or ignorance about the life. So, there are no good or bad Karma generated for their thinking or actions.2. If there is no self or a soul, then how rebirth exist?Buddhism teaches there is no part which we can treat as self or soul, among material or non-material parts of a living being. All of material and non-material parts are existing as huge sequences of base units and we conventionally treat as a living being. When we think scientifically a living being is a huge collection of various kinds of atoms. Similarly Buddhism teaches there is an ultimate entity of matter (may be fundamental particle as in the science) which is very much smaller than an atom called as Rupa-kalapa. Life time of a Rupa-kalapa is very short but when one dies one or many new Rupa-kalapa arises. Similarly there are ultimate entities for non-material parts (related to the mind); lets simply call it as Citta. Citta is not like material entities, it can only exist one at a time. When one dies another one arise instantly without any delay. Life time of a Chitta is very small (Smaller than trillions part of a second). So, non-material part is like a huge Citta stream but one arises after one. When our last Citta vanish from the body next Citta arise at a new place as a new being without any delay since a Karma. Citta stream doesn’t end since it’s craving to exist. Before the last Citta vanish, Citta stream will remind a past Karma. So, this Karma will power the new life. But nothing goes from past life to new life. But we can't treat new life as a different being. Since new life arise since the past life. For an example, think about your image from a mirror. Image arises since you and we treat image as yours but it is a different thing. Similarly you should think about the new being after death. New birth is not the same being but also not a different being.3. What is the definition of enlightenment?'Spiritual Enlightenment' can be defined as gaining the perfect knowledge about the life or about the four noble truths.As Buddhism teaches no one can't give this perfect knowledge with words or even with telepathy. Individuals have to self-realize it. Only some approximate assumptions can teach according to the teacher's teaching power. Those assumptions can be;Three Marks of ExistenceAll worldly things are Impermanent, suffering and non-self.Four Noble TruthsCycle of rebirth is suffering, Suffering is due to cravings, Cravings can be overcome, Path to overcome the cravings is the Threefold Training (or Noble Eightfold Path).Threefold TrainingPractice moral virtue (Five precepts, Eight precepts etc.), Get higher level of mind concentration (Samatha Meditation), Get higher wisdom to analyze these assumptions (Vipassana meditation). These three steps can’t separate such as complete one and then complete other. These three steps have to develop cyclically again and again till the enlightenment.Five aggregate definition of a living being (Collections exist as a living being without any soul)Self-view of a Chitta stream existed for a very long time without any beginning in cycle of rebirth. So, it is difficult to remove this self-view. Buddhism defines a living being in different ways to give a better realization. We previously defined a living being as combinations of non-materiel and material things exist as generations without any permanent part. In this definition we think a being as a collection of sense bases (eye, ear, nose, tongue, body, and mind) and sensation processes. From the touch to sensation whole process can be dividing in to five steps. There is a non-ending huge sequence of Chitta stream within a living being. When sensation this Chitta stream shift to different places to process the sensation. When a being living, huge amount of sensation processes arises and these collections called as Five Aggregates. Buddhism defines a living being as a huge collection of sensation processes without any soul. 1. Sense triggers (Rupa) For a normal being, there are six internal-external (organ-object) pairs of sense bases;1. eye and visible objects, 2. ear and sound, 3. nose and odor, 4. tongue and taste, 5. body and touch, 6. mind and mental objects(such as past memories)One of six kind of trigger came from one of six external sense bases (Ayatana). Then it case to arise a sense trigger in one of internal sense bases. Then one sensation process starts. Chitta stream will shift and process the sensation with many thought processes (Chitta-viti). When we are sleep such as when there is no trigger from eye, ear, nose, tongue, body or mind Chitta stream only contain Bhavanga-Chitta. Bhavanga-Chitta always exists from the conception when there is no thought process. Bhavanga-Chitta doesn’t allow to stop the Chitta stream. To see an image, there will be huge amount of thought processes.All material things may case to arise sensation triggers. So, material things can be treat as sense triggers. But, non-material mental objects also can trigger a sensation process. So, we can’t think only matter as sense triggers. 2."Sensation" or "feeling" (Vedanā) Process of sensory experience of an object. It is either pleasant, unpleasant or neutral. 3."Perception" (Saññā) Sensory and mental process that registers, recognizes and labels (for instance, the shape of a tree, color green, emotion of fear). 4."Karmic formations" (Saṃskāra) '"Constructing activities", "Karmic activities". In this step Karmas are generating. 5."Consciousness" (Vijñāna) "Discrimination" or "discernment". A series of rapidly changing interconnected discrete acts of cognizance related to the trigger.Example of Vipassana Meditation. Looking five aggregates as Impermanent, Suffering and Non-self;“These Sense triggers are not me. There is no part within Sense triggers which can treat as me.”“These feelings are not me. There is no part within feelings which can treat as me.”“These perceptions are not me. There is no part within perceptions which can treat as me.”“These Karmic formations are not me. There is no part within Karmic formations which can treat as me.”“These consciousness are not me. There is no part within consciousness which can treat as me.”“All of these five aggregates are not me. Those are just results of some causes. These five aggregates are impermanent, suffering and non-self.”“So, There is no thing as me. All things are just results of some causes. All things are Impermanent, Suffering and Non-self”Dependent Arising (Cyclic chain of causes and results which explain the endless cycles of rebirth.)****Two causes of past lives****1) Ignorance, 2) Karmic Formations****Five percent results since past causes****3) Rebirth-consciousness (first mind of a new birth), 4) First materiel embryo base unit and mind base five aggregates, 5) Arising sense spheres; eye, ear, nose, tongue and skin 6) sense spheres triggers or contact s 7) Feelings****Three cause of current life****8) Craving, 9) Grasping, 10) Good or Bad Karmas case to a birth****Two future results since cause of current life****11) Birth, 12) Ageing & DeathIf we could perfectly remove ‘1) Ignorance’ with getting perfect knowledge about the life then there are no ‘2) Karmic Formations’. Then there will not be ‘3) Rebirth-consciousness’. Then there will not be ‘4) First materiel embryo atom’. … And so on.Enlightenment is the final result of a gradual process (For example; Clean defilement, Gain mind concentration, Gain knowledge, Increase the awareness and realize the reality in some amount. Again, Clean more defilement, Gain more mind concentration, Gain more knowledge, Increase the awareness and have a better realization about the reality, …. ). Enlightenment is the final result of all Threefold Training(Noble Eightfold Path). How permanent enlightenment possible?There are Seven Factors of Enlightenment:Mindfulness (Sati)Investigation of Dhammas/Reality/Four Noble Truths (Dhamma-vicaya)Energy to continue (Viriya)Joy or rapture (Pīti)Relaxation or tranquility of both mind and body (Passaddhi)Mind Concentration gained with meditation (Samādhi)Equanimity maintain all of these factors(Upekkha)To experience the final Magga-citta, it is important to develop all of these factors in a balanced way. Reading this answer will develop your 2nd factor 'Investigation of Dhammas'. But this don't develop other factors in a balanced way. So most likely, you will not experience a Magga-citta. But, if you have developed other factors before in this life or in a previous life, there is a possibility of experiencing a Magga-citta with balancing all factors. (After doing mediation, you can try calmly reading this answer again.) Lord Buddha teaches us the best way to develop these factors are Four Mindfulness or Satara-Satipatthana Meditation.This kind of assumption knowledge (also called as 'Parathogoshaka-Prathya') can only give by a rightly self-awakened Lord Buddha or by a his disciple. This answer has enough assumption knowledge for an extremely intelligent person to reach Enlightenment without doing hard practices in the 'Threefold Training'. If anyone could reach Enlightenment since this answer, it is not because of me but because of the teachings of Gautama Lord Buddha. If Lord Buddha didn’t teach these facts, I will not be able to tell you these facts with my own wisdom.To read more about, how Buddhist practice and develop these wisdom to attain ultimate happiness, please study Satipatthana Sutta.The Foundations of MindfulnessThe Way of MindfulnessFree 10-day course from www.dhamma.org ( Find the nearest meditation center to you from this link: World wide locations. Attain the highest possible happiness in the universe. You don't have to change your religion if you are not a Buddhist.)