The word Karma is derived from the Sanskrit Kri, to do; all action (includes. thoughts, words and deeds) is Karma. Technically, this word also means the effects of actions. In connection with metaphysics, it sometimes means the effects, of which our past actions were the causes. But in Karma-Yoga we have simply to do with the word Karma as meaning work.…
As pleasure and pain (as result of our thoughts, words and deeds) pass before his soul they have upon it different pictures, and the result of these combined impressions is what is called man’s “character”. If you take the character of any man, it really is but the aggregate of tendencies, the sum total of the bent of his mind; you will find that misery and happiness are equal factors in the formation of that character. …
Karma in its effect on character is the most tremendous power that man has to deal with. Man is, as it were, a centre, and is attracting all the powers of the universe towards himself, and in this centre is fusing them all and again sending them off in a big current. Such a centre is the real man — the almighty, the omniscient — and he draws the whole universe towards him. Good and bad, misery and happiness, all are running towards him and clinging round him; and out of them he fashions the mighty stream of tendency called character and throws it outwards. As he has the power of drawing in anything, so has he the power of throwing it out.
All the actions that we see in the world, all the movements in human society, all the works that we have around us, are simply the display of thought, the manifestation of the will of man. Machines or instruments, cities, ships, or men-of-war, all these are simply the manifestation of the will of man; and this will is caused by character, and character is manufactured by Karma. As is Karma, so is the manifestation of the will.
The men of mighty will the world has produced have all been tremendous workers — gigantic souls, with wills powerful enough to overturn worlds, wills they got by persistent work, through ages, and ages. Such a gigantic will as that of a Buddha could not be obtained in one life, for we know who his fathers was. It is not known that his fathers ever spoke a word for the good of mankind. Millions and millions of petty kings like Buddha’s father had been in the world. If it was only a case of hereditary transmission, how do you account for this petty prince, who was not, perhaps, obeyed by his own servants, producing this son, whom half a world worships? It cannot be solved by the theory of heredity. The gigantic will which Buddha threw over the world, whence did it come? Whence came this accumulation of power? It must have been there through ages and ages, continually growing bigger and bigger, until it burst on society in a Buddha, even rolling down to the present day.
All this is determined by Karma, work. No one can get anything unless he earns it. This is an eternal law. We may sometimes think it is not so, but in the long run we become convinced of it. A man may struggle all his life for riches; he may cheat thousands, but he finds at last that he did not deserve to become rich, and his life becomes a trouble and a nuisance to him. We may go on accumulating things for our physical enjoyment, but only what we earn is really ours. A fool may buy all the books in the world, and they will be in his library; but he will be able to read only those that he deserves to; and this deserving is produced by Karma. Our Karma determines what we deserve and what we can assimilate.
We are responsible for what we are; and whatever we wish ourselves to be, we have the power to make ourselves. If what we are now has been the result of our own past actions, it certainly follows that whatever we wish to be in future can be produced by our present actions; so we have to know how to act (in thought, word and actions).
~ Excerpted from the Complete Works of Swami Vivekananda