THE WAY TO NIBBĀNA (1)
"This Middle Path leads to tranquillity, realization, enlightenment and Nibbāna."
-- DHAMMACAKKA SUTTA
The way to Nibbāna is the Middle Path (Majjhimā Patipadā) which avoids the extreme of self-mortification that weakens the intellect and the extreme of self-indulgence that retards moral progress.
This Middle Path consists of the following eight factors: Right Understanding, Right Thoughts, Right Speech, Right Action, Right Livelihood, Right Effort, Right Mindfulness, and Right Concentration.
The first two are classified as Wisdom (pa257;), the second three as Morality (sīla), and the last three as Concentration (samādhi).
According to the order of development Morality, Concentration, and Wisdom are the three stages on the
These three stages are embodied in the beautiful ancient verse:
Sabba pāpassa akaranam --
etam Buddhāna sāsanam.
To cease from all evil
To cultivate good
To purify one's mind --
This is the advice of all the Buddhas.
We reap what we sow. Evil results in pain, and good in happiness. Our pain and happiness are the direct results of our own good and evil.
A person with a right understanding realizes this just law of action and reaction and, of his own accord, refrains from evil and does good to the best of his ability. He does so for his own good and for the good of others. He considers it his duty to live as a blessing to himself and to all others.
Knowing that life is precious to all and that none has any right whatever to destroy the life of another, he extends compassion and loving-kindness towards every living being, even to the tiniest creature that crawls at his feet, and refrains from killing or causing injury to any living being.
There is no rule that one is to be preyed upon by another. However, the strong do mercilessly kill the weak and feast on their flesh. This is animal instinct. Such actions by animals are excusable because they know not what they do, but when those who are gifted with reason and understanding perpetrate such crimes, there is no excuse. Whether to satisfy one's palate or as pastime, it is not justifiable to kill or to cause another living being to be killed. If the killing of animals is wrong, how much more heinous is it to kill human beings -- individually or collectively, employing brutal or so-called civilized methods -- for the sake of peace, religion, or any other seemingly good purpose?
Honesty, trustworthiness, and uprightness also are the characteristics of a person with right understanding. Such a person tries to abstain from all forms of stealing "whether in its dissembled or obvious forms." Abstaining from sexual misconduct, which debases the exalted nature of man, he tries to be pure and chaste. He avoids false speech, harsh language, slander and frivolous talk and speaks only what is true, sweet, kind and helpful. As certain drinks and drugs promote heedlessness and mental distraction, he avoids intoxicating liquor and cultivates heedfulness and clarity of vision.
These elementary principles of regulated behaviour are essential to one who treads the Path to Nibbāna, chiefly because they tend to control both deeds and words. Violation of them introduces obstacles that hinder his moral progress on the Path. Observance of them means smooth and steady progress along the Path.
Having progressed a step further in his gradual advance, the aspirant now tries to control his senses. To control craving for food and to promote buoyancy of mind and body, abstemiousness or fasting at least once a month is advisable. Plain and simple living is preferable to a luxurious life which makes one a slave to passions. A life of celibacy is recommended, as one's valuable energy thus conserved could then be utilised wholly for the intellectual and moral welfare of oneself and others. In such a life one is detached from additional worldly bonds that impede moral progress. Almost all spiritual teachers, it would appear, have nourished their bodies sparingly and have led a life of strict celibacy, simplicity, voluntary poverty, and self-control.
While he progress slowly and steadily, with regulated word and deed and sense-restraint, the Kammic force of the striving aspirant compels him to renounce worldly pleasures and adopt the ascetic life. To him then comes the idea that:
"A den of strife is household life,
And filled with toil and need,
But free and high as the open sky
Is the life the homeless lead. "
Thus realizing the vanity of sensual pleasures, he voluntarily forsakes all earthly possessions, and donning the ascetic garb tries to lead the Holy Life in all its purity.
It is not, however, the external appearance that makes a man holy but internal purification and an exemplary life. Transformation should come from within, not from without. It is not absolutely necessary to retire to solitude and lead the life of an ascetic to realize Nibbāna. The life of a Bhikkhu no doubt expedites and facilitates spiritual progress, but even as a layman Sainthood may be attained.
He who attains Arahantship as a layman in the face of all temptations is certainly more praiseworthy than a Bhikkhu who attains Arahantship living amidst surroundings that are not distracting.
Concerning a minister who attained Arahantship while seated on an elephant decked in his best apparel, the Buddha remarked:
"Even though a man be richly adorned, if he walks in peace,
If he be quiet, subdued, certain and pure,
And if he refrains from injuring any living being,
That man is a Brahmin, that man is a hermit, that man is a monk. "
There have been several such instances of laymen who realized Nibbāna without renouncing the world. The most devout and generous lay follower Anāthapindika was a Sotāpanna,  the Sakya Mahānāma was a Sakadāgāmi,  the potter Ghatikāra was an Anāgāmi  and King Suddhodana died as an Arahant. 
A Bhikkhu is expected to observe the four kinds of Higher Morality -- namely,
Pātimokkha Sīla -- The Fundamental Moral Code, 
Indriyasamvara Sīla -- Morality pertaining to sense-restraint,
Ājīvapārisuddhi Sīla -- Morality pertaining to purity of livelihood,
Paccayasannissita Sīla -- Morality pertaining to the use of the necessaries of life.
These four kinds of morality are collectively called Sīla-Visuddhi (Purity of Virtue), the first of the seven stages of Purity on the way to Nibbāna.
When a person enters the Order and receives his Higher Ordination (Upasampadā), he is called a Bhikkhu. There is no English equivalent that exactly conveys the meaning of this Pāli term Bhikkhu. "Mendicant Monk" may be suggested as the nearest translation, not in the sense of one who begs but in the sense of one who lives on alms.
There are no vows for a Bhikkhu. Of his own accord he becomes a Bhikkhu in order to lead the Holy Life as long as he likes. He is at liberty to leave the Order at any time.
A Bhikkhu is bound to observe 220 rules,  apart from several other minor ones. The four major rules which deal with perfect celibacy, stealing, murder, and false claims to higher spiritual powers, must strictly be observed. If he violates any one of them, he becomes defeated (pārājikā) and automatically ceases to be a Bhikkhu. If he wishes, he can re-enter the Order and remain as a Sāmanera (novice). In the case of other rules, which he violates, he has to make amends according to the gravity of the offence.
Among the salient characteristics of a Bhikkhu are purity, perfect celibacy, voluntary poverty, humility, simplicity, selfless service, self-control, patience, compassion and harmlessness.
The life of a Bhikkhu or, in other words, renunciation of worldly pleasures and ambitions, is only an effective means to attain Nibbāna, but is not an end in itself.