Buddha was one of the earliest psychologists of human history. Modern Psychologists are impressed by the vast psychological knowledge present in the Buddhist doctrine. When investigating the mind to find the cause and cessation of suffering, Buddha took an approach that is similar to the scientific method employed in modern scientific research.
The collection of canonical texts revered as exclusively authoritative in Theravada Buddhism is known as Tripitaka, which means ‘Three baskets’.
Here is a short description of those three baskets:
(1) The basket of expected discipline from monks (Vinaya Piṭaka)
It consists of rules and regulations of monastic life including dress code, dietary rules and prohibitions of certain personal conducts.
2) The basket of discourse (Sūtra Piṭaka, Nikayas)
This is the collection of discourses given by Buddha,
(3) The basket of special doctrine (Abhidharma Piṭaka)
This includes technical, analytical and systematic content with deep insights into the psychology human mind. It was taught by Buddha to his most eminent disciples.
Apidhamma talks about two truths: Ultimate truth (Sammuti Sacca)and Conventional truth (Paramattha Sacca):
Conventional truth: The world we perceive which appears to have individuals interacting with each other is the conventional truth. We use our conventional language to express different things in the conventional truth. The idea that there is an individual self which is the essence of a human being is an apparent reality but ultimately, there is no individual self or essence.
This concept of a relative truth also exists in Vedanta, which is called Vyāvahārika (vyavahara), or samvriti-saya.
Ultimate truth: When we look at the truth in ultimate level, there is no self or an entity in reality. All that exist are aggregates or skandhas. The five aggregates or heaps are: form (or matter or body) (rupa), sensations (or feelings, received from form) (vedana), perceptions (samjna), mental activity or formations (sankhara), and consciousness (vijnana). These five aggregates completely explain a sentient being’s physical and mental existence.
So, anything you think as individual is actually made up of these five aggregates each of which are “not I, and not myself”. According to Buddha, clinging to these aggregates as if they are real is what causes suffering.
When we negate all these aggregates as not self, that which remains is ‘sunyata’ translated as ‘emptiness’ in English. But Buddha chose to express everything in negative terminology and hence Sunyata just explains what it is not. According to that definition, the reality, the ultimate truth which exists is free of any essence, anything that can be conceived by mind or senses.
But this ‘Sunyata’ in Buddhism and the ‘Brahman’ described in Vedanta is actually the same. The problem with the word Brahman is that it lets one to imagine Brahman as something, an entity or an essence. But even the Vedantic texts say that Brahman cannot be described in words because it is not possible to objectify it in anyway. It is not possible to mentally conceive an image or description about Brahman but it can be realized and seen as the truth of everything we perceive, by direct experiential knowledge. There is a term called ‘Anubhava’ which has the aspects of both experience and knowledge of the absolute truth. In Vedanta, this absolute or ultimate reality is called as Vyāvahārika satya (vyavahara), or samvriti-saya.
Buddhism goes even deeper than Vedanta in explaining psychological aspects of human thought.
Dhammas
The reality can also be described in terms of Dhammas.Dhammas are the ultimate entities or momentary events which make up the fabric of our experience of reality. The conventional reality of substantial objects and persons is just a conceptual construct created by the mind on a constant flow of dhammas which appear and disappear.
There are four categories of dhammas:
Citta – It is one’s mindset, or state of mind but cannot be classified as an aggregate because it is neither an entity nor a process.
Cetasika (mental factors, mental events, associated mentality)- the mental factors are categorized as formations (samskaras) concurrent with Citta. There are 52 types of Cetasika.
Rūpa — (physical occurrences, material form), 28 types
Nibbāna — (Extinction, cessation). This dharma is unconditioned it neither arises nor ceases due to causal interaction.
Many other concepts such as svabhava and causality exist in Buddhist psychology. In Buddhism, a deep insight into a person’s mind stream to see the impermanence, suffering and anatta (non-self) in everything perceived in a person’s citta is stressed for the cessation of suffering.
The core practice of Buddhist path to liberation is mindfulness. Being mindful of one’s moment to moment experience including thoughts, sensations, volition, states of mind etc with non-judgemental attitude, openness and acceptance gives insights into workings of the mind and ultimately leads to cessation of suffering and Nirvana.
A simple outline of this spiritual path excluding all its complex theoretical structure is explained in my post ‘Awakening through Mindfulness’.
I have explained my own journey in the following articles:
2.Spiritual enlightenment – Is it a Myth or Real
Shanmugam's Blog 