The Sanskrit word karma (कर्म) derives from the root verb kR (कृ): to do. So karma is literally action. SwAmi JnAneshwara BhArati has a set of very lucid articles on karma that are worth reading to gain the necessary background on karma that this article presupposes. Karma is a very important concept for the sAdhaka to understand because a true understanding of karma is needed to understand the mind in meditation. A sound understanding of karma can also positively influence the aspirant's actions in the external world, and thus improve sAdhanA tremendously. This is because the stabilization of external interactions enables quicker access to greater depth in meditation. A thorough understanding of karma also gives faith that sAdhana is never in vain, even if at certain times it appears that there is no spiritual progress in spite of intense practice.
Since there are many interpretations of what karma actually means, this can sometimes lead to misunderstanding and confusion. At a basic level this can sometimes lead to a dilemma in the aspirant's mind as to whether karma is a belief or a truth. For instance, in his otherwise excellent book "Advaita VedAnta: A Philosophical Reconstruction" Eliot Deutsch argues that the concept of karma is a "convenient fiction". This is a misunderstanding stemming from analyzing VedAnta as a philosophical construct through an intellectual lens, while ignoring the practical aspect of VedAnta as a way of life. Recall that Indian darshanA-s are Revelations that are meant to be experienced through spiritual sAdhana and not analyzed in dry intellectual terms. Here we clearly see the value of direct experience as opposed to mere intellection. In order to understand karma in VedAnta one has to understand that the proper study of VedAnta presupposes a mastery of Yoga, where karma plays a very central role. The key to understanding karma lies in the Bhagavad Gita and the Yoga Sutra. It is definitely not a "convenient fiction", but a very practical reality that every sAdhaka must confront head-on: both in external life and in sAdhanA.
The other source of misunderstanding comes from the tendency among many people, particularly Indians, to ascribe every misfortune in life to karma. This has led people to think that a belief in karma implies a kind of fatalism. Neither of these misinterpretations is useful to the aspirant. As we shall see below, karma can be understood in very simple terms. It is optional for the aspirant to provisionally accept some of the successive levels of its operation as belief, to be revealed later through direct experience.
In the context of Yoga and VedAnta the word karma is used with an implicit reference to the Law of Karma. Just as we have the law of gravitation in the physical world, the law of karma is another law of Nature. The law of karma is that all our actions bear fruit, unless these actions are truly selfless. The first part of the law does not call for a great act of faith. Everyday we see that our actions bear fruit. If the qualification regarding selfless action is not immediately acceptable to someone, even that is not necessary for sAdhanA. In time this can become clear with even a little direct experience of the working of the mind through meditation.
Now even if one accepts that actions bear fruit, sometimes a doubt may arise regarding karma because we see 'bad things' happening to 'good people' and vice versa. There are two reasons for this. The first is that our notion of 'good' and 'bad' is subjective. What appears 'bad' at one time for an individual may later be perceived as 'good' for the same person. The other reason for this is that the fruits or consequences of karma may not be experienced immediately. In fact, since Yoga and VedAnta state that the jIva (or semi-mortal self) goes through several lives, one may experience the fruits of karma over several lifetimes. The aspirant can take the second reason as a provisional belief, or even choose not to.
But there is another important aspect of karma that cannot be ignored, which is that the fruits of karma are not experienced purely in the physical world. In fact, the greatest impact of karma is in the mental plane through the creation of habit patterns, or grooves in the unconscious mind, called samskAras. Our lives would be considerably freer were it not for this aspect of karma. The coloring of rAga (attachment to pleasurable objects) and dvesha (rejection of unpleasant phenomena) that we attach to the fruits of almost all our actions cause the mental imprints of karma to deepen our habit patterns in the unconscious mind. We end up doing more of what we like and less of what we don't like. Eventually these habit patterns become so deeply ingrained that our reactions to many of life's situations are automatic. One of the goals of Yoga is to de-automatize our mental reactions to everyday phenomena so that we can 'see things as they really are'. This is because it is only through the mind field that is free of these colorings (aklishta) of rAga and dvesha is Reality perceived 'as it is'. For this to happen one has to have a sound understanding of how karma works to create our mental thought patterns in the first place. This understanding is gained intuitively in meditation by observing the working of the mind. Herein lies the importance of understanding karma for the purpose of sAdhanA.
Since karma leads to samskAras that in turn determine the mind field, the skillful discharge of karma in external life is equally important. One of the most important observations in the Bhagavad Gita is that karma is unavoidable.
niyatam kuru karma tvam karma jyAyo hyakarmaNah
sharIrayAtrApi ca te na prasiddhayedakarmaNah (BG III.8)
Perform the prescribed duties: for action is superior to inaction.
Moreover, if you are inactive, you will not be even able to complete the journey of your body (maintain your body).
No one can live without acting. This is very important for the aspirant to internalize because at an advanced stage in practice when the construction of reality by the mind is fully exposed in meditation there can be a great revulsion against performing any action in the external world. Here the Gita comes to the rescue and shows the sAdhaka the way to integrate spiritual growth into external life.
Karma for self-preservation is to be distinguished from other karma. The other karma can then be further divided into that which is obligatory (since it stems from one's dharma), and that which is optional or voluntary. One who understands dharma and karma knows how to act skillfully in life. That is the import of the phrase (yogah karamasu kaushalam: yoga is skill in action). The key point is that if all optional or voluntary action (that is other than that required for self-preservation and the upholding of dharma) is performed selflessly, then that action does not bind the yogi. That is why it is said in the Yoga Sutra:
karma ashukla akRshNam yoginah trividham itareshAm (Yoga Sutra 4.7)
The actions of yogis are neither white nor black, while that of the others is threefold.
Another subtle point is the distinction between action (karma) and the Actor (kartA). Ordinarily we think that we are the actors (kartA) who enact our action (karma). This I call the myth of agency. But in the depths of meditation when Consciousness is uncovered as our true nature, then one realizes that this Witnessing Consciousness never acts. The myth of our agency leads us to believe that things will fall apart at work or family if we do not act. This is nothing but our bloated sense of self-importance that comes from our ahamkAra (ego). When someone dies we see that the rest of life around them goes on without skipping a beat. All the people, institutions and projects that we think are dependent on us are really not. Through our own ego we develop an 'Atlas complex': that we sustain the world around us. Nothing could be farther from the truth! The truth is we do not know our true nature, which is not our mind or our ego.
When the constructs of the mind, and indeed the mind itself, are known to be composed of the three guNas, then the true meaning of the verse from the Bhagavad GIta becomes clear:
prakRteh kriyamANAni guNaih karmANi sarvashah
ahamkAra vimUDhAtma kartAham iti manyate (Gita III.27)
Actions are done in all cases by the guNas of PrakRti.
He whose mind is deluded by egoism thinks, 'I am the doer'.
In fact, this why prakRti (pra meaning first, or that which came before, and kRti, or making) is called prakRti: it is the first and original doer or Actor. One also then understands why Sri KRshna exhorts Arjuna to be 'nistraiguNyo' (or beyond the three guNas) in the verse
traiguNya vishayA vedA, nistraiguNyo bhava arjuna (Gita II.45)
The VedAs deal with matters related to the three guNas, but be beyond the influence of the three guNas O Arjuna!
Here by Veda, Sri KRshna means the brAhmaNas that are part of the karmakANda and deal with the ritual observances, and not the Upanishads that form the jnAnakANda, and which deal with matters beyond the three guNas.
The Bhagavad GIta is a comprehensive source of all the Upanishadic wisdom related to karma. However, many of the verses require prolonged contemplation and then intuitive understanding of their import dawns through meditation. Merely reading them or reciting them does not enlighten the reader in the same way. In fact, sometimes the verses can seem baffling, or paradoxical. Some of the most impenetrable verses in the GIta are those related to karma or action. These verses can be understood by a sAdhaka through intense practice and this is how a yogi has true knowledge of action. For instance, it is said:
karmaNyakarma yah pashyedakarmaNi ca karma yah
sa buddhimAn manushyeShu sa yuktah kRtsnakarmakRt (BG IV.18)
He who sees action in inaction and inaction in action is wise amongst men
He is yoked (poised) and a performer of all actions
Although on the face of it the literal translation of this verse is quite simple, it is very profound. What is meant by seeing action in inaction? If a person who is not self-realized sits inactively, this does not mean that the act of their existence ceases to bind to them. Being slothful or lazy does not mean karma does not attach to a person. Freedom from action comes only through the realization that one's true Self is Purusha or Consciousness who never acts, and that all acts are performed by PrakRti through the three guNas. So there is action in inaction if there is no wisdom or Gnosis. On the other hand, when yogis, sages or self-realized persons act, this is truly inaction because it is selfless and non-binding. The import of the final part of this verse is that when the yogi sees that his true nature is Purusha, and that Purusha and PrakRti have in fact emerged from the same Brahman, then it becomes clear that he is the performer of all actions.
Although it is not immediately obvious, the fruit of our karma is inexorably moving us towards the path to the Self. This becomes clear provided we are willing to listen to the feedback from our past karma, and invest in sAdhanA.