The function of divination is to better understand how to unite the internal personal universe (the microcosm) with the external universe (the macrocosm). This is the goal of all true religion and occultism, as well as the larger purpose of divination regardless of what kind we use. It is for this reason that Crowley said that unless a person is a "Master of the Temple", divination is better left alone, due to the possibility of error on our part, due to an imbalanced personal universe. This is why religions are concerned and disapproving of divination, as there is a real danger of insanity occurring when a person begins mapping their internal universe and microcosm. It is for this reason that astrology gives a unique opportunity to the aspirant in that, if used correctly, the individual is given the "solution" to the "equation" he was attempting to solve, and is able to "check the answers" in order to learn how his direct observation was or was not in line with the external universe. Other divination systems do not have this benefit and depend more on a person's actual ability to perceive reality directly in a spiritual sense. Both have advantages, but I bring this up to explain that unfortunately, most people do not understand the real special value that Jyotish gives to the practitioner. If you look at a person's face and begin observing all the features, you estimate where their Jupiter is, their Moon, etc. and write it all down. You can then use the natal chart to adjust your perception of the person, which-- if done over and over with new people-- always gives you an objective correction as to what errors you made in your perception of reality. For example, you believe a person has Rohini rising but upon getting their birth time you discover it is in Leo; however, you see this person does have Moon and Venus in the first house, the combination of which produces a very similar energy to Rohini. Now you had a slight adjustment in your internal universe and perception in order to better distinguish extremely subtle nuances in a person's being, recording this in your mind for the future. The novice, instead of training his perception with Jyotish, attempts to distinguish himself and match his misaligned internal Universe with something by rearranging the details of the already established, proven, and agreed upon system, often by creating new ayanamshas, or using mixtures of tropical and sidereal, or some other strange novelty instead of contributing their efforts to the already established system. Rather than rearranging a system while trying to project your misaligned internal Universe onto something physical, rearrange your internal Universe to match what is present. The current reforming of Jyotish is a result of over-intellectualization that is not matched with gnosis and true perception. You have to have broken through the Rudra Granthi and transcended the throat center to do divination for others; otherwise, when you reach the throat center (which requires a person to go beyond duality) the person begins disintegrating, due to not being able to handle non-dual consciousness and go beyond knowledge and reason, tapping into intuition and gnosis. This is why tradition is so important, because tradition we first follow and do not understand (based on faith) and then through working with it (where we first follow on faith, arranging our internal Universe to match it) we then attain gnosis and understanding of why the tradition was indeed correct, realizing the phrase "truth endures". This touches upon the mysteries of Rahu and the illusory nature of knowledge and reason. A person has to go beyond reason and knowledge, or they will actually go insane. A person can rationalize absolutely anything; the only thing keeping people from doing so are the interpretative guidelines of tradition. Rahu is said to destroy and attack tradition because he represents individuals who overly rely on their rational and individual mind, and so believe that the traditional worldview is incorrect, seeking to become a reformer or revolutionary.
I mentioned insanity above, and want to better clarify the very real possibility if a person begins using any divination system too early. The quote from Crowley about waiting until a certain level of spiritual perception is developed before beginning is ironic, because if a person reached the grade of "Master of the Temple" they actually have no need to do divination in the average sense, because at this level of consciousness every phenomenon around them is interpreted and understood as a direct communication with God. The person at this stage, however, is in actuality the only type of person who can perform divination for others without severe dangers lurking. If a person, when they attempt to do any divination, begins rearranging an already established tradition instead of contributing to the tradition, you can already see the beginnings of insanity, as they begin developing an inflated ego and a delusion of grandeur, as their own personal universe begins losing its connection with the macrocosmic universe, and so they begin developing a sense of paranoia and "us against them mentality" to everyone who tells them that their divination system is wrong. A true adept can use any established divination system and produce startling gems of insight, which confirms the tradition and contributes more to the understanding of that cosmology and categorization system of the universe. The insane would-be adept states that the established tradition is wrong, and seeks to produce strange rearrangings of the cosmology, which reflects the schizophrenic state occurring in their own psyche. This is why tradition is so important as it is the bastion and vanguard against the darkness and chaos of the abyss, and this is why Rahu creates insanity and also attempts to destroy all tradition. In order to avoid going insane through overreliance on the intellectual aspect of religion or any divination system, a person must develop a direct connection to God, and work on and perfect his own internal universe so it actually matches the external. This is the goal of religion and occultism, and a person must reach a certain level of proficiency in his level of internal purification to "get his ego out of the way" so to speak, in order for his readings to not be tainted and distorted due to his own internally imbalanced state. This is a state of Gnosis, Understanding and direct connection to God, which renders him impervious to certain elemental, planetary, and even sorcerous influences on his mind, which can lead a person to insanity if he relies on the falsity of his intellect. This is because there, in actuality, is no possibility of "pure reason", which was explained clearly in the writings of Emanuel Kant, especially in his work "A Critique of Pure Reason", explaining how whenever a definitive statement is pronounced, its contradiction is called forth immediately. Dwelling on this fact for too long can produce an existential crisis on the novice, and result in actual insanity due to an inability to transcend "Pure reason", creating a mental state where any information presented to them is immediately disintegrated and picked apart in their mind. due to the dispersion present within them from creating an unbalanced Universe and worldview. Not only this, but possession and obsession from negative entities tampering with the readings, as well as the negative forces and entities attacking and distorting the clients mind, all come after the reader, and if a person does not understand this, it is only a short time after he sets up shop performing Jyotish readings or anything else that he begins on the descent into insanity and madness due to his ignorance.
Example of Insanity
Frater Achad, real name Charles Stanfield Jones, was the initial star pupil of Aleister Crowley. He produced unusually gifted writings on the Hermetic Qablah and the Tree of Life, showing an early mastery of interpreting the Hebrew Alphabet and the mystical science of mantras and letters. Initially, he used the accepted tradition and produced wonderful contributions to anyone interested in letter mysticism, and who understood the associations of the Hebrew letters to the tree of life. However, all of the sudden, he decided to claim the grade of "master of the temple" spontaneously, which is anyone's right to do so at any time. However, immediately after this, paranoia began setting in, and he began to believe he was meant to destroy Crowley, and that all of the traditional attributions to the Tree of Life were wrong. He began reversing the traditional attributions of the Hebrew letters on the tree of life and began stating that the old attributions were "wrong", and that he was meant to reform the tradition, and had others up against him who wanted to cover up the "real" knowledge. Crowley warned him in various letters that if a person gains real mystical insight into something and begins publishing works, those works must conform to certain established standards and shed light on an established tradition, rather than attempt to turn it on its head (he literally reversed the tree and turned it upside down) rather than create an entire thing that no one can understand or agree upon and which enriches or contributes nothing to anyone. Of course, Achad actually continued on with his distorted internal universe until he finally was actually committed to an insane asylum. Individuals who attempt to perform readings for others should look closely at themselves for these classic signs of insanity. A key way to identify this behavior is the "us against them mentality" and also a desire for others to "submit" to the obscure system they create, which they are led to believe that others simply cannot understand. This is a way of pressuring people into submission, as they like to create the image that they are a spiritual master and deserve students and servants due to their "lofty attainments". A person who solidifies their ego in an imbalanced and false universe is unfortunately slowly disintegrated by the force of time because they cut themselves off from the source of light and truth that one only has access to if they maintain contact with the external universe internally. Due to this lack of energy, they pump themselves up as a cult leader or spiritual figure in order to drain the energy of others, in an attempt to ward off the disintegration that is happening to them at all times. A person who does this has actually lost their soul, and will disperse at some point in time, despite whatever methods they use to preserve themselves initially. This is why it is much better to wait until you are ready to perform divination for others, and enter into the period of complete retreat and prayer while waiting for Gnosis before attempting to "help" others. Consider that before you can help others, you must first help yourself.