Preparing to See More Clearly
If we're honest, most of us find Zen masters', mystics' & saints' behaviors & writings incomprehensible, counter-cultural, unnatural even. But from their vantage point, it is we who are confused, seeing things "through a veil of illusion." Zen goes so far as to say that we sleepwalk through life, profoundly misperceiving things - as if seeing things upside-down ("inverted views").
Our vision only slightly clarifies spontaneously with age. Buddhist, Native and other spiritual traditions have long-established practices specifically designed to efficiently draw back this veil of illusion. These spiritual practices tend to be held in supportive cultural environments & preceded by lengthy initiations to adequately prepare participants for a radically different perspective on reality. In Buddhism well-established morality, loving-kindness (metta) & compassion are considered necessary prerequisites (context or 'set & setting') before even starting meditation practices. Without this preparation, progress in meditation is thought to be impeded. In our current Western culture, such preparation is seldom mentioned, and rarely if ever emphasized in secular mindfulness courses.
Clarification of vision or evolution of consciousness can also suddenly speed-up due to trauma, certain drugs (eg psilocybin, ayahuasca), or various other factors. Without appropriate preparation, set & setting, the sudden pulling back of the veil of illusion can be traumatic: http://jglovas.wix.com/awarenessnow#!Meditations-Potential/c17jj/565b14520cf221f2a7a5e228
"Set" refers to the person’s mental orientation toward the experience. This includes mental health, emotional maturity, morality, personality, goals, openness to change, etc.
"Setting" refers to the place where this takes place - ideally a well-supervised, safe, supportive setting.