Ajahn Mun’s Teaching :
The goal that the disciple must keep constantly in mind is to escape the suffering associated with the ordinary human condition, which means that the kilesa must be uprooted, that is to say, the uncontrolled wandering of the citta (consciousness), carried away into harmful mental and emotional states, must be stopped.
To achieve this, one must begin by establishing a certain mental calm; constant repetition of a word like “Buddho” is a necessary support in the beginning, this word “Buddho” being a reminder of the possibility of awakening for the meditant.
The disciple must take as the basis of his/her practice the heart of the Buddha’s teaching, contained in the part of the Satipatthana Sutta consecrated to the body: ceaseless attention to the movements of the body when walking, eating, moving, etc., as well as investigation into what the body is in order to liberate oneself from all attachment to it. Attention to the body brings the disciple constantly back to him/herself in the present and prevents him/her from becoming dispersed towards the exterior.
The disciple must, as much as possible, eradicate possibilities for distraction through a solitary life and struggle against desires via an ascetic way of life and strict obedience to all the precepts of the monastic discipline to which Ajahn Mun attached great importance.
Ajahn Mun had used danger as a means in his practice; he would advise it constantly to his monks, both to keep in mind the thought of bodily death as well as to kindle a state of awakening in the present. He emphasized the necessity of practicing in places that awakened fear and avoiding places that were too tranquil. He assured his disciples that unless they lived in an environment that would force them to concentrate inwardly, it would be difficult for them to attain a stable state of calm and their meditation would suffer because of this. He taught them that danger forces one to be attentive and alert at every moment. No one, he said, could hope to transcend “dukkha” if that person succumbed to fear of death when faced with what might be thought a frightening place. In the face of danger, the attention should be focused on Dhamma and not sucked outwards. The meditant may then experience a feeling of safety and an unshakable strength of soul. He said that his inspiration for meditation had its basis almost exclusively in the fact of living in perilous surroundings, which was the reason why he taught his disciples to be determined to confront them. He also claimed that if someone possesses Dhamma in his/her heart, animals can sense it and that exerts a quieting influence on them. This mysterious power of the heart was something that everyone must experience individually. He, himself, had succeeded in possessing it to the supreme degree.
The disciple draws on an important support in the practice of samatha, a form of meditation that focuses on a single support with a view to producing states of absorption (samãdhi) bringing about a felicity that encourages the disciple in her/his practice, but she/he must be careful not to become attached to it.
Mindfulness is used intensively, alongside development of the meditative practice of calm and concentration. Practiced continually, it transforms into a superior consciousness that feeds the highest degrees of wisdom.
By the word wisdom is meant directed concentration that takes as its object an aspect of Dhamma to which the disciple must apply all his/her energy; it is not an intellectual reflection, but sustained concentration that brings up flashes of intuitive comprehension, making it possible to see things as they are: impermanent, unsatisfying, and devoid of self. The “penetrating vision” that results from this is the very means of the ultimate liberation from the “self.”
Self-transformation is not easy; Ajahn Mun would later repeat this often to his disciples; one has to act on different planes at the same time. To develop beneficial mental states, the disciple must cultivate the four eminent qualities (Brahma Viharas): loving kindness, compassion, altruistic joy, and equanimity. These different means lead gradually to inner transformation.
As Ajahn Mun knew that the fact of being able to read their thoughts might trouble the monks, he tried to help them indirectly by giving teachings on themes such as the damage one does oneself when one becomes lost in harmful thoughts:
“The battlefield for conquering the kilesa exists within each individual who practices with wisdom, faith, and perseverance as weapons for fighting his way to freedom. It is very counterproductive to believe that you have plenty of time left since you’re still young and in good health. You should not focus your attention outside of yourself. Since they are constantly active, pay close attention to your actions, speech, and thoughts to determine the kind of results they produce. Are they producing Dhamma, which is an antidote to the poisons of apathy and self-indulgence; or are they producing delusions that cause dukkha, suffering? The heart and mind must be trained in order to obtain optimum results. Only after death are we beyond the need for training.”
From Journeys in Lands of Awakening and Sainthood