As we have said earlier, Patanjali has singled out pramana, or “valid”, “true” knowledge, as the first vritti. However it strikes the eye here that, unlike with all other vrittis, when speaking about pramana the Yoga Sutras author has not only provided its definition but has also listed the main concepts of traditional Indian gnoseology. That is, he has listed the "right" sources of knowledge: the direct (own) perception, the authoritative evidence and the logical inference. In general such view is inherent in many theories of gnoseology of Indian philosophical systems (see, for instance, the "Indian Philosophy"of S. Radhakrishnan). Moreover, in some systems they used to single out not three sources of knowledge, as Patanjali did, but four of them, adding the mystical knowledge as an additional "valid" means. Thus there come two questions:
1. Why was Patanjali that specific in distinguishing pramana if it is just the same vritti?
2. Why did Patanjali, being a mystic, ignore singling out mystical knowledge as a “valid” means of obtaining the true knowledge?
The answer to the first question shall in fact come as the reflection on the theory of cognition role in mystical Tradition. Though the Yoga Sutras of Patanjali seems to be not a philosophical treatise yet a practical one, it still does contain this gnoseological remark about what is the true knowledge and what is not.
In my view it is this very remark that is conditioned upon the need for developing the principles of thinking that will enable one to harmoniously advance within this system of mystical knowledge.
In every tradition, especially if this tradition is an esoteric one, a question about reliability of the obtained knowledge is always present. If the knowledge is associated with some purely physical things the determination of such reliability shall be a rather easy process . Yet how sure can we be of the “non-material” knowledge or mystical concepts? How certain can we feel of our own visions, insights, commentaries given by other people, and so on? After all, the mysticism, like everything that is associated with a person, is a rather tricky sphere. The occurrence of various glitches and mistakes is always possible, especially in the beginning. Even the great healers and people who ‘see the things through’ can make mistakes. Sometimes it happened that the whole systems were subject to “malfunction”, both those from old days and the ones of modern days. For instance, there still exists a whole trend of modern occultism called channeling that is the practice of obtaining knowledge from spirits, extraterrestrial creatures and so on. And although a major part of such ”knowledge” comes as mere non-informative prophetic visions or moralistic teachings a la “aspire to the Light”, while the doomsday dates predicted by the channelers have never happened to come true, people still continue their practice without a second thought about eventual drawbacks of the “practice” itself. And there were also many others who were “good” at prophesying in this manner...
Here I shall make an early reservation that being a practicing esoteric I undoubtedly admit the possibility of receiving knowledge by means of mystical experience. It’s like Jung used to say in reply to a similar question: “I don’t need to believe, I KNOW”. However in this sphere one also needs some criticism and respective culture and as a rule this is what lacks behind the insights of the so called “wild” extrasensory perception adepts.
I shall also specify my position: in any system that has some minor relation to the man and his advance skipping the mystical experience is not possible. Even modern psychology that tried to do it due to considering itself a scientific study finally had to come to researching such states through Jungian studies, transpersonal and humanistic psychology (Maslow) . Fogging mystical and spiritual topics by means of quasi-scientific and delusive categories such as “a unified energy and information space” or “torsion fields” is a pointless thing to do. One’s denying the significance of mystical experience in our field usually results in falling into the most childish forms of acquiring this experience, like dowsing or using the “pendulum”.
Thus we see that the mystical experience is necessary, but at the same time it is dangerous. In order to somehow protect oneself from the state of falling into glitches – one’s own or those of other people – one needs to have a specific level, principles of thinking. The more solid these principles are - i.e. one has mastered the skill of, say, intellectual verification of some new knowledge within the system of the self-established worldview, or within a system of some traditional worldview, or within a common paradigm - the more chance one has to keep oneself from following some newly occurred “bugs”.
Here are some analogies. In scope of the Roman Catholic Church that comes as the most delicately set religious organization  there exist a very well developed science of theology - the science of God, all sorts of reasoning about the miracles that may be true, untrue, and so on. It would seem here: what does the believer need the theology for? Look at the Protestants – just believe, and that’s it! Yet when Catholics speak, nothing is that easy. From their perspective, according to their worldview, there are at least two powers existing in this world: the divine power, and the power of the devil. And so a person cannot be sure whether some idea, thought and experience was casted by one power or inspired by another one. In order to be sure they need to set a system that could provide for such confidence, that could most accurately and reliably interpret the scriptures, would enable interpretation of miracles, mystical revelations and so on. Therefore, if the Catholic Church has to deal with some phenomenon that can be regarded as a miracle and a manifestation of holiness, they set a special commission consisting of representatives (including the secular ones) of various sciences - physics, chemistry, medicine, and they consider the question of whether this miracle could have any natural grounds. If their answer is negative and they fail to determine that there are any, the battle is joined by experts in demonology and ethics. Their job is to determine whether this wonder could come as a manifestation of demonic power. They define this by means of long-term consequences. For instance if a person who was subject to miraculous healing proceeds to become a criminal the miracle is deemed as the undivine, and so on. It is obvious that physics and chemistry, as well as the moral standards, were changing along the process of human evolution and things that we would a century ago have for a miracle that the science is not able to explain today comes as a question of technique only, but it is the principle here that is interesting to us, the willingness to dissect the mystical experience using the tools of intelligence, logic and common sense.
Similar questions occurred to both Orthodox Christianity and Hesychasm. They have a well-developed doctrine of the “spiritual charms, or prelesti” [=charms, delusions; since the concept of “prelest” is inherent to Orthodox teaching only and is absent in the Protestant-Catholic doctrine, this word is usually transliterated. However in order to make it for the English-speaking reader in line with the following explanations we also use the word “charm” in the meaning “temptation”, “delusion” - translator’s note]. What are these charms? The charms are not something that is nice and pretty in terms of the ordinary language. The charm is something that charms, tempt. In fact, it is the same very vritti. Something that attracts, attaches to itself. When Hesychasts practice their techniques they assume that on their way they may come across some certain confusions – these very charms / prelesti. There are primitive charms, emotional ones, for instance, some delusion, ignorance, emotional attachment, but there are other charms as well. A whole section is completed by intellectual prelesti, such as euphoria from intellectual understanding, when a person ceases with spiritual knowledge and starts to work with intellectual one. Or, say, the delusive prelest that occurs when one gets more delight from telling about the mystical experience that from practicing it. There are charms related to mystical revelations. For instance, the false vision of the Tabor Light (the uncreated energies). And then comes the task: to sort one from the other. And this task can be completed, in particular, by means of “logos”, or rational principle, that is in fact the theory of gnoseology applied to the ascetic practice.
You can find the same in psychological practices of Catholicism, for example, the spiritual exercises of Ignatius Loyola. He describes a whole range of the states that in scope of spiritual practice come as pathological, if to say it in our language.
Sufism also warns one of spiritual dangers in terms of its well-considered theory of cognition called Kashf. We shall not speak about it in details now, though we may come back to it in some of the following articles. The core point here is that it does exist.
A well-considered and critical theory of cognition, the willingness to use one’s intelligence distinguish a solid School and Tradition from a very young or a home-bred one. The Tradition is also characterized by accumulation and transfer in generations of experience of working with eventual mistakes occurring in scope of the practice.
I shall thus sum it up: the point of the line dedicated to pramana is not only that it describes the forms of obtaining the valid knowledge, but also that the line says that in order to successfully practice any mystical techniques one must have specific principles of understanding the relevant experience that [i.e. the principles – translator’s note] need to be developed. This development should be based, in particular, upon intellectual platform.
As far as the second question is concerned - why Patanjali has not introduced mystical knowledge as the fourth "legal" way of cognition - I so far suggest that the reader thinks on this topic on his own.
 Although it is not so easy here as well. Most of glitchy concepts about Egyptian pyramids as created by extraterrestrial creates can be easily disproved just upon going there and seeing the pyramids on one’s own, however these “theories” continue to live against any evidence.
 One can find more information on this topic in my monographs, for instance, the “Psychological Practices in Mystic Traditions…”
 Of course, religion is incomparable to the esoteric systems but in this context they come in contact through the unity of the object - the mystical experience.