Buddhist practice engenders awakening, and enlightenment is central to Buddhism. Buddhist lore includes unsurpassed, complete, perfect enlightenment, e.g., Buddha's enlightenment. The lore also includes incidents of Zen students experiencing sudden enlightenment as a result of listening to the chanting of a sutra, or of being inspired, or unexpectedly whacked, by a Zen master.
Suzuki Roshi said zazen practice is like walking in a fog; "eventually your clothes get wet clear through". In another context, he said that enlightenment seems extraordinary mostly to those who pursue it; but it is more analogous to motherhood, which may seem very special to aspiring mothers but not to those who are mothers.
Kobun Chino Otogawa Roshi said, (in the context of several talks on Kobun's 1973 Discussions:
... When people awake, they awake like coming out of a dream. Some awaken very fast. Some need the last day of their life to wake up from the dream. ... "Oh my gosh, I am the last one! What was I doing?" ...
It is not just work of the intellect. With whole body you awaken, whole world is awakening too. And when you awake you find, "Oh, this is it. That was not it". Even after awakening you do not say "I don't need to sit any more". In a very strong sense awakening becomes sleep. When you say, "This is it," and when you abide in it, it becomes again deepest dream. So constant effort is the essential of our life. That means life is the conquering of death. So constant effort is the conquering of death.
Most Zen students experience many minor awakenings over the years, as well as a subtly increasing sense of transparency within ourselves and our practice, and a sense of being increasingly permeated by the very sweet energy of nature, nirvana, or emptiness. The sense may include returning to a more natural way of being, and/or of dropping off complexes or neuroses, particularly those associated with our ego-mind's internal dialogues and desires to attain success, property, prestige, sex, wealth, power, fame, or glory.
As this gradual process of awakening continues over some years, one's sense of compassion and reverence, or devotion, progressively increases, along with increasing awareness of our basic state or source, that includes emptiness, cognizance or knowing, and openness, not confined to anything. Fearless Simplicity, a book by Tsoknyi Rhinpoche, describes the process, (albeit the book is about Dzogchen, rather than Zen).
The actual experience of being awake and alive, consciously as a human, involves incredible and inexplicable paradoxes. Sleep apparently alternates between deep sleep and dreams that range from impersonal movies to intensely personal fantasies and nightmares. In our ordinary experience, on awakening from sleep our minds usually resume their normal egocentric perspectives that vary enormously in terms of emotional involvement and understanding of underlying drives and aspirations. Our bodies benefit from stretching, as in yoga and similar exercises. Awakening one's spirit warrants practices of meditation. Buddhist practice support these aspects of awakening through its vast teachings. Yet the central fact, the miracle of being alive and conscious, is available to every one in every moment, without any special practice.
In our ordinary experience of growing up from childhood, a kind of false self or ego is forged from unconscious emotions that interact with repetitive thoughts, and from habitual aversions, preferences, and attachments. Ego effects how one acts and what one feels, causing unneeded suffering; (see Some Key Aspects of Buddhism). What we think of ourselves and of each other is diminished by our egocentricity and our selfishness. Over time, habits of mindlessness may limit our awareness, and can virtually cripple us. This can become quite tortuous. Yet in fact one's physical body is something else; its atoms were formed in the evolution of stars, and the evolutionary development of its molecules, cells and organs took millions of years. Even social inheritance and language evolved over hundreds of generations. Each individual inherits from family and society as well as evolution. Whether our minds and consciousness itself are material or immaterial has not been fully determined. The meaning and purpose of life reflected in spirit is even more deeply mystical.
Many enlightenment experiences are short-lived perceptions that yield to feelings of normalcy. Through Zen practice we may physically occasionally sense or become aware of ongoing physiological changes, and aspects of our egos may prove empty and vaporize before our eyes. These aspects usually reflect unconsciously-held complexes of emotions, beliefs, ideals and values that over time may have become engraved into our brains and muscles, particularly those associated with our posture, spine and face. When we become fully conscious of them they may relax and dissolve, sometimes slowly. Ego changes but survives to mediate between our id and super-ego, our basic urges and our understanding of behaviors that will work within social contexts.
While most of us cannot claim the clarity of a sage or Zen Master, our practice still cultivates mindfulness and addresses suffering for the benefit of all.