"The deed (karma) produceds a fruit under certain circumstances; when it is ripe, then it falls upon the one responsible. For a deed to produce its fruit, it must be morally good or bad and be conditioned by a volitional impulse, which in that it leaves a trace in the psyche of the doer, leads his destiny in the direction determined by the effect of the deed. "

(exerpted from "The Encyclopedia of Eastern Philosophy and Religion", Shambhala Books, 1994)