Because of our ignorance (avijja) of these Noble Truths, because of our inexperience in framing the world in their terms, we remain bound to samsara, the wearisome cycle of birth, aging, illness, death, and rebirth. Craving propels this process onward, from one moment to the next and over the course of countless lifetimes, in accordance with kamma (Skt. karma), the universal law of cause and effect. According to this immutable law, every action that one performs in the present moment — whether by body, speech, or mind itself — eventually bears fruit according to its skillfulness: act in unskillful and harmful ways and unhappiness is bound to follow; act skillfully and happiness will ultimately ensue. As long as one remains ignorant of this principle, one is doomed to an aimless existence: happy one moment, in despair the next; enjoying one lifetime in heaven, the next in hell.
The Buddha discovered that gaining release from samsara requires assigning to each of the Noble Truths a specific task: the first Noble Truth is to be comprehended; the second, abandoned; the third, realized; the fourth, developed. The full realization of the third Noble Truth paves the way for Awakening: the end of ignorance, craving, suffering, and kamma itself; the direct penetration to the transcendent freedom and supreme happiness that stands as the final goal of all the Buddha's teachings; the Unconditioned, the Deathless, Unbinding — Nibbana (Skt. Nirvana).
Because the roots of ignorance are so intimately entwined with the fabric of the psyche, the unawakened mind is capable of deceiving itself with breathtaking ingenuity. The solution therefore requires more than simply being kind, loving, and mindful in the present moment. The practitioner must equip him- or herself with the expertise to use a range of tools to outwit, outlast, and eventually uproot the mind's unskillful tendencies. For example, the practice of generosity (dana) erodes the heart's habitual tendencies towards craving and teaches valuable lessons about the motivations behind, and the results of, skillful action. The practice of virtue (sila) guards one against straying wildly off-course and into harm's way. The cultivation of goodwill (metta) helps to undermine anger's seductive grasp. The ten recollections offer ways to alleviate doubt, bear physical pain with composure, maintain a healthy sense of self-respect, overcome laziness and complacency, and restrain oneself from unbridled lust. And there are many more skills to learn.
The good qualities that emerge and mature from these practices not only smooth the way for the journey to Nibbana; over time they have the effect of transforming the practitioner into a more generous, loving, compassionate, peaceful, and clear-headed member of society. The individual's sincere pursuit of Awakening is thus a priceless and timely gift to a world in desperate need of help.http://www.accesstoinsight.org/lib/authors/bullitt/theravada.html