Jñana yoga is the last phase of the process toward Self-realization, and the only one to focus specifically on Vedanta (knowledge derived from the Upanishads). This is in contrast to karma yoga and upasana yoga, which are considered prerequisite for hearing the knowledge imparted during the jnana yoga phase. The idea is that we must first make the mind fit through various practices and disciplines so that the knowledge is able to go in. Where the first two yogas are centered on action, the last phase is focused on knowing. In the spiritual world, there are many yogis who are "doers” but few who are actual “knowers.” There are a number of reasons for this including attachment to spiritual experiences, lacking the courage to seek the truth, and because the knowledge is counter-intuitive, requires a qualified teacher, and necessitates repeated exposure in order for it to be first realized and then, actualized.
In the Bhagavad Gita, Krishna tells Arjuna to “Make no mistake, what I am sharing with you is indeed, a profound secret.” (4.3) Jñana or “Self-knowledge” is a secret because as individuals, we are conditioned to identify with the body-mind rather than that which illuminates the body-mind—consciousness. This is due to the proximity of the body and the intimacy of our thoughts.
As already mentioned, Self-knowledge is also easily misunderstood because it’s counterintuitive. For example, the Sun appears to rise in the East and set in the West every day. And yet, even once we have learned that it's the motion of the Earth and not the Sun that makes it appear to set and rise, we continue to perceive the opposite. It’s for this reason that it is said that Self-knowledge is the one secret that even once told, still remains a secret! In short, jnana yoga is a process; an unfolding that slowly fills out the picture regarding the nature of our experience, and provides the tools for getting out of samsara.
Vedanta suggests four qualifications for gaining jnana. Sometimes abbreviated as “The Four D’s” they include discrimination (viveka), dispassion (vairagya), discipline (shatka sampatti) and burning desire (mumukshutva). Discrimination is the ability to tell the difference between that which is true (i.e. the Self; pure consciousness) and that which is not (i.e. objects; that which is impermanent and comes and goes). Dispassion is what is gained through maturity and the understanding that all objects are not real (are of the nature to change; not substantial). Dispassion is also the outcome of karma yoga which teaches non-attachment to the results of one’s actions. Discipline is about having control of the senses and having mastery of, what Vedanta refers to as, the “organs of action” used to express oneself in the world (hands, legs, speech, etc.). Discipline is typically developed during the upasana yoga phase and often defined to as the “six kinds of wealth” (shatka sampatti), which include mastery of the mind (shama), mastery of the sense organs (dama), the ability to withdraw from sense objects (uparama), forbearance (titiksha), faith pending verification (shraddha), and concentration of the mind (samadhana).
Lastly, desire means having a burning desire for freedom. As the choice of words suggests, this isn’t just a meek interest in obtaining spiritual freedom. Most people with a burning desire may have already tried other spiritual practices with limited success, and Vedanta is their last resort. They are also mature enough know that the world cannot provide real happiness—only the temporary kind—and instead, are seeking something they can rely on for lasting satisfaction.
If you are a seeker, you may already have the above mentioned qualifications to some degree. But in most cases, they will need to be made stronger before advancing to jnana yoga. For one who is already qualified, understanding of Vedanta will come easily and learning will be a pleasure. Like running a marathon or swimming a mile—you’re either ready for jnana yoga or you’re not. One must have the fitness and the desire to cross the finish line. Some seekers might even find that they need to re-qualify after learning Self-knowledge. They realize that in order to progress in their spiritual journey, they still have areas which need work, for example, karma yoga and gaining a sense of humility.
We can divide jnana yoga into three stages: shravana, manana, and nidhidyasana. The first, shravana, is listening to the teachings for an undetermined length of time from a qualified teacher who is able to unlock the meaning of the teachings (prakriyas). This may involve putting a temporary hold on our beliefs that we have developed over a lifetime. Vedanta can often sound counter-intuitive because ignorance is hardwired, which is why it’s important to approach it with an open mind.
Manana, the second stage, is the removal of any doubt left over from hearing the teachings and is characterized by a period of question and answer between student and teacher. Manana is marked by much reflection, and clarifying, and testing the logic of the teachings.
Lastly, nidhidyasana is the removal of habitual behavior (leftover binding tendencies) and the assimilation of the teachings. In the shravana stage, one would say, There is the Self. But in the nidhidyasana stage, one would say, I am the Self. This cognitive shift, from realizing “there is the Self” to actualizing it as “I am the Self” is what leads to liberation (moksha). It is also what separates the academic study of Vedanta (indirect knowledge) from actual Vedanta as a vehicle for freedom (direct knowledge).
But jnana yoga isn’t really about acquiring knowledge, more than, the removal of ignorance through a process that includes qualified guidance, repetition and constant discrimination (between what's "real" and what's not). This is because ignorance is tenacious and just learning Self-knowledge doesn’t guarantee that it will stick. One must still do the work, absorb it and integrate it.
Once Self-knowledge is gained, it’s like a set of tools we can make use of on a daily basis. So, first we must obtain the right tools, and then we must apply them to the task at hand (in this case, the removal of ignorance). The result is the slow elimination of that which binds us, and prevents us from seeing that we are already free.