Karma means action. The term comes from the Sanskrit root "kri" which means "to do". Therefore, all actions which we do, consciously or unconsciously, are karma. Every karma has its result; every cause has its effect. But the cause will not end just with the effect; instead the effect itself will become the cause of other effects, just as one sows a seed which sprouts into a tree. There the seed is the cause and the tree is the effect, but the effect does not end by becoming a tree. It will yield hundreds of fruits which will brings thousands of seeds; and those seeds when sown again will become trees. Thus, karma is an endless chain of cause and effect. The doctrine of karma means this--the law of cause and effect.
Karma in relation to people becomes duty. When a man marries a woman, a duty arises. Similarly, when a couple beget children, karma takes the shape of the duty of those parents toward their children and the duty of the children toward their parents. In relationship with the idea of rights, the concept of duty widens. Thus, the duty of a man includes his community, country, world, etc.
The Indian rishis have found that man comes to this world with five debts, or becomes indebted to five principles or persons:
Matri rina--indebtedness to the mother
Pitri rina--indebtedness to the father
Deva rina--indebtedness to the gods
Rishi rina--indebtedness to the sages and gurus
Atma rina--indebtedness to the soul
Indebtedness to parents is for giving us the body, loving care, protection and education, and for continuing the progeny. Looking after them with all reverence during their ailments and old age and obeying their righteous commands may release the soul from these two debts.
Deva rina, or debt to God and gods, is fulfilled by thankfulness to the nature deities and the supreme God for giving us the privilege of human birth; for rain, food , light, air, earth and the infinite bounties with which to liver here happily; for giving us the heart to feel and the intellect to discriminate. Such devotion and worship is considered to be good, as it may bring us the blessings of the celestials and God, by whose grace our soul may find rest and peace.
We are indebted to the sages and gurus who have sacrificed their lives to find the Truth, but for whom we would have been left in the darkness of ignorance regarding our purpose of life, the nature of God and soul and their relationship, the way to reach God and innumerable facets of the Truth. Studying the message which they have given and acting according to their advice with great respect and reverence, may alone release us from the debt we owe to them.
Last is duty toward our own soul. Questions about duties really surround the foremost duty which is toward our own individual soul. To release the soul from the bondage of karma, to make it attain enlightenment and liberation, is the one goal of all religions and religious duties. Meditation, devotion, yoga, truthfulness, sincerity, purity, right speech, right conduct, prayer to God, study of scriptures, service to masters, service to humanity, all that is good and divine which will bring light, wisdom, bliss, peace and liberation is the duty of everyone toward his own soul.
The very fact of our birth is decided by karma. The benefits which the soul receives from others makes it indebted to those from whom it received its benefits. Indebtedness brings bondage, unless we clear it through service and thankfulness.
A statement in the Gita (IV:37) declares all karma is reduced to ashes by the fire of knowledge. It should be known that only those effects of karma which have bound the soul are totally burnt by the fire of knowledge in him who obtains such knowledge. It does not mean that he will have no more work; instead, he will then be working selflessly. He will do divine works in accordance with the Divine Will; this work will not bring him bondage. Such selfless action performed through wisdom is called karma yoga. Selfish action is karma (cause) which will bring karma (effect); the performance of karma (duty) as a puja (worship) will bring jnana (wisdom), which burns all karma (the cause and effect of selfish actions).
The motive force in karma is selfish desire and its fulfillment; the motive power in karma yoga is selfless love and the renunciation of desire for the fulfillment of God's work. Both are karma (action); but one binds, and the other releases. What is the reason? Motive. In karma, it is the motive which decides its results.
(Essence of Bhagavad Gita and Bible, p. 31.)