It is almost impossible to have a variety of mystical experience that has not been thoroughly accounted for in the Buddhist scriptures.  According to the Nyingma tradition of Tibetan Buddhism, there are nine vehicles or yanas which define a hierarchy of valid approaches to awakening [1]. Since Salinger and the beats introduced the concept to the counter-culture, the way of the bodhisattva has been touted as a popular ideal, but a closer investigation of differences among the first three vehicles reveals a more accurate picture beyond superficial glosses and hopeful self-imaging.  In this schema, the Mahayana path of the bodhisattva is listed as the third in an ascending order, followed by the outer and inner tantras and culminating in Dzogchen.

The first or original vehicle, is also known as Theravada or hinayana buddhism consists of four stages

In the Buddha's day, the attainment of arhathood was considered the highest realization possible.  This viewpoint would be challenged by the rise of the Mahayana schools a few centuries later.  The second vehicle is the way of the solitary-realizer or pratyeka-buddha which outlines a constellation of views and attitudes in some respects resonant with the aspirations of the modern western spirituality. The rest of this article will attempt to define the strengths and weaknesses of the pratyeka path from a Mahayana perspective. I have included excerpts from the Surangama Sutra to help elucidate and qualify various experiences and their relation to the vehicles.

This following quote describes the attainment of an insight arising in the course of meditation, a moment of bliss occurring in the mind-stream of one who, like many psychedelic pioneers, has had inadequate training.  The Buddha explains:

    In this still state, as form vanishes and receptiveness manifests, the practitioner's wisdom may grow out of proportion and much in excess of his dhyana, and he may wrongly think that he has achieved the highest attainment and has reached the rank of Vairocana.  So he is satisfied with a little progress which he regards as complete.  This is his mind losing its usual insight and being misled by his (discriminatory) knowing and seeing.  If he understands this, it will be harmless, but if he regards it as sainthood, he will succumb to the inferior self-satisfied demon who will control his mind, causing him to boast that he has realized Supreme Nirvana.  He will thus lose all benefit from the dhyana so far achieved and will fall into the lower states.

The expansive flash of cosmic consciousness triggered by psychedelics transports the witness beyond the brain-mind with great force, but the incapacity of one's meditation and prior spiritual development condition the response to this epiphany.  Buddha's reference to mind's 'usual insight' indicates that this experience arises in the mind-stream of one who has already attained a degree of equanimity and subtle discrimination.  Even the bliss of samadhi, if not properly understood and integrated, can become a source of error and serious distraction from the intention to become enlightened for the sake of all sentient beings.

Here is another quote from the Surangama Sutra in which the Buddha is describing the serial dissolution of the five skandhas, the elements, both physical and psychological comprising what we ordinarily identify as a self.[2]  At this point in his description, the first three aggregates, namely bodily form, feeling and perception, have already 'become void' and the meditator observes the cessation and relative emptiness of all activity.  An extraordinary expanse of seemingly infinite consciousness is all that remains.  No doubt, this experience has been mistaken for the ultimate ego-death for as long as there have been yogis and trippers:

As the practitioner looks exhaustively into volition (the fourth skandha) which now becomes void, he will wipe out birth and death but will not yet achieve Nirvana.  If he clings to consciousness as his refuge, he will interpret that his body and mind as well as the whole of space spring from that refuge, thereby wrongly inferring that this source is true Reality, free from birth and death.  Because of his misinterpretation of vijnana (consciousness; the fifth skandha) as permanent, he will understand neither the Uncreate nor (the created) birth and death.  For his delight in this deluded state, he will fall into error because he mistakes impermanence for permanence and will thus become an adherent of Isvaradeva, (the universal self who creates all things), thereby screening his Bodhi nature and missing the Buddha-knowledge.

This is an extraordinarily subtle description of a mystical state wherein one is released from identification with samsara but has not yet realized Buddhahood.  The line stating that 'he will wipe out birth and death' refers directly to an insight associated with the temporary dissolution of the skandha of volition, the active principle of karma.  This particular cessation makes it possible to mistake a very subtle form of consciousness which remains, for the ultimate ground of existence.  Because of the intoxicating bliss of such a samadhi, one may persist in this erroneous belief and generate karmas on the basis of imperfect understanding.  According to the text, such an attainment is equivalent to mystical communion with the divine essence and the basis for an experiential belief in a creator God, a highly valued realization in many of the traditional contemplative orders both east and west.  According to Buddha, imperfect knowledge of such experiences is an obstruction to the realization of supreme Buddha-knowledge.

Shakyamuni explains that the precise nature of this error consists in taking a glimpse of the causal mind as the ultimate attainment.  As the practitioner contemplates the depths of the bright and pure essence of consciousness, he may regard it as nirvana and not strive to advance further.  This is the brass ball on the top of the 100 foot pole.  In consequence of a distortion so fine that it requires a Buddha to point it out, the untrained practitioner will become one of those whose minds are set on what is termed 'pratyeka-buddhahood,' the path of the lone learners, or the solitary-realizers.

This list of possible errors in the course of training is found at the end of the Surangama Sutra where they are classified by the Buddha as

...states of dhyana leading to wild speculations because the practitioner relies on delusion and regards inadequate achievement as full realization.  

The fact that these errors have grave consequences, hasn't robbed the Buddha of a devilish sense of humor as he tells us that such karmas are further compounded by the aspirant wrongly declaring that he has realized supreme Bodhi, and thus breaking the rule against lying!

In an effort to qualify methods suitable for people of different capacities, Shakyamuni Buddha named three vehicles or means of conveyance to the state of awakening.  Originally, the divisions of arhat, pratyeka and Fully Enlightened One clarified three types of realization.  In early Buddhist parables these were symbolized by a goat cart, a deer cart and a bullock cart respectively, all of which are used in the metaphor to entice a group of children at play to come out of a burning house; samsara.  Over time, the three divisions  became viewed as different spiritual ideals of which the latter was considered by far superior.  To this end, much of Mahayana literature systematically criticizes the lesser paths to encourage practitioners to move beyond relative enlightenment and sainthood toward the ultimate realization of Buddhahood.

The arhat or 'foe-destroyer' is a disciple of the Buddha who has overcome all afflictive emotions and realized emptiness, but the capacity to transmit this to others is generally limited by a life of dogmatic purity and renunciation.  The pratyeka-buddha or 'solitary realizer' has attained a degree of awakening without  the benefit of a lineage or a teacher, although his stance outside the lineage provides very limited means of transmission. He enjoys a deep intuition of absolute emptiness, yet phenomena still appear to his senses as inherently existent. As these solitary-realizers are bereft of instruction, they are also unable to found a tradition.  This is not to say that they will not try to do so or that they must necessarily live alone in a literal sense.  Their solitude refers to distance from a practicing lineage.  The pratyeka path can serve to train the mind and inner peace, but does not lead to full awakening.  Although the final fruit of this vehicle is the same emptiness realized by a Buddha, the bodhisattvas cultivate a more subtle, penetrating cognition of this emptiness than solitary-realizers.

The ill-founded and unquestioned belief in a separate self is the root of all egoity.  Freedom lies in realizing the non-inherent, interdependent existence of all objects and conceptual designations.  The way of the bodhisattva approaches this understanding through a wider variety of skillful means than the hearers and solitary-realizers.

In the Sutra on the Merits of the Fundamental Vows of the Seven Buddhas of Lapis Lazuli Radiance, the Masters of Healing, Buddha states that pratyekas are unable to have faith and comprehend the profound range of activities of the Tathagata. 

This is due to a sediment of coarse conceptions regarding the status of objective existence, precluding the understanding of the bodhisattva-yana.  To such a one, the admonitions of the great realizers of times past and scriptural statements which should be understood literally are unwittingly taken as metaphor and the secret meaning of many symbols, parables and analogies are misunderstood or overlooked.  Herein lies the importance of an oral tradition for clarification of doctrinal points and correct application of practical antidotes to residual ignorance.

According to Longchenpa, an enlightened Tibetan master and scholar of the 14th century, the pratyeka-buddhas are among those 'sons of the Buddha' who comprise the exoteric sangha while the tantric masters are to be regarded as the actual knowledge and lineage holders.

The Ratnagotravibhaga Mahayanottaratantrasastra illustrates the uncommon and yet incomplete nature of the pratyeka's realization by saying that in such a person, the essence of being is present like a treasure in the home of a pauper without his knowledge.  

In his exposition of the tenets systems, Konchog Jigme Wangpo (1728-1791) explains that solitary-realizers are those who have met with teachers and listened to their teaching of the doctrine in previous lives but in their final life live in samsara peacefully and by themselves, like a rhinoceros.  They are said to be proud and independent-minded and because of this, they choose not to meet with teachers or study doctrine in this life.  Because the solitary-realizer's practice has been motivated by an individual longing to transcend cyclic existence, there are still egoic predispositions in his mental continuum to be purified before the realization of Buddhahood.  

It is not uncommon for solitary realizers to congregate and live in community with others for awhile but there is also the  'rhinoceros' kind who prefer to live alone and say very little about the Doctrine.  According to some schools, even after attaining such a realization,  there is the distinct possibility that the understanding of a pratyeka-buddha may degenerate to the point where he once again becomes a 'stream-enterer, 'a term referring to those who are at the beginning of the path leading to arhathood. 

Although considered intellectually inferior to pratyeka, the stream-enterer has overcome fundamental doubt and hesitation in relation to the Buddha's teachings. Like the pratyeka-buddha, the 'hearer' is no longer dependent upon herd morality or external disciplines as though they were by themselves a sufficient means to enlightenment. Both stream-entere rs and pratyekas enjoy a measure of liberating insight into the illusion of selfhood.  

The shortcomings of the pratyeka-buddha-yana are made evident in the following quote by Gen-dun Drub (1391-1474), the first Dalai Lama:

    Accomplishment of the three higher trainings results in personal nirvana; yet this is not a sufficient spiritual attainment.  The two types of nirvana-attainer, that is, the Sravaka-Arhats and Pratyeka-buddhas, do in fact abide in nirvana; but they've completed merely a fraction of the abandonments and insights concomitant with full enlightenment.  Consequently they cannot be said to have fully achieved ultimate benefit for either themselves or others.  Sooner or later they must turn to the path leading to Buddhahood, the state of full enlightenment that has completed all abandonments and insights.  One day a Buddha will send them rays of light from his inspiring presence, and will admonish them to enter the Mahayana path and become Buddhas themselves.  It would be much more expedient to aim for full Buddhahood from the very beginning of ones practice; and to take up its cause which is the Mahayana vehicle.

The present Dalai Lama has explained that one can be a follower of the Mahayana by tenet and yet still be a low vehicle practitioner (hearer/solitary-realizer), by path. The opposite is also true.

In the Lankavatara Sutra, Buddha explains the different types of practitioners and the part that inveterate tendencies play in determining the nature of their realizations.  The 'second class of masters' introduced here refers to pratyeka-buddhas. Some of these will eventually transcend this cul-de-sac and become stream-enterers.

    The second class of masters are those who have gained a high degree of intellectual understanding of the truths concerning the aggregates that make up personality and its external world but who are filled with fear when they face the significance and consequences of these truths, and the demands which their learning makes upon them, that is, not to become attached to the external world and its manifold forms making for comfort and power, and to keep away from the entanglements of its social relations.  They are attracted by the possibilities that are attainable by so doing, namely, the possession of miraculous powers such as dividing the personality and appearing in different places at the same time, or manifesting bodies of transformation.  To  gain these powers they even resort to the solitary life, but this class of masters never get beyond the seductions of their learning and egoism, and their discourses are always in conformity with that characteristic and limitation.  

 Among them are many earnest disciples who show a degree of spiritual insight that is characterized by sincerity and undismayed willingness to meet all the demands that the stages make upon them.  When they see that all that makes up the objective world is only manifestation of mind, that it is without self-nature, un-born and egoless, they accept it without fear, and when they see that their own ego-soul is also empty, un-born and egoless, they are untroubled and undismayed, with earnest purpose they seek to adjust their lives to the full demands of these truths, but they cannot forget the notions that lie back of these facts, especially the notion of their own conscious ego-self and its relation to Nirvana.  They are of the Stream-entered class.

Beyond any occult understanding of the references to '...miraculous powers such as dividing the personality and appearing in different places at the same time, or manifesting bodies of transformation,' these abilities can also be understood in the contemporary sense of worldly fame; a powerful social influence co-joined with the wonders of electronic media, publishing and modern transportation.

[1]   Nine Yanas or vehicles

[2 ] The FIve Skandhas