The law of Karma works in this way: if I have given sorrow there will be some form of sorrow returning to me. It may not be precisely in the way that old-fashioned people would speak about an 'eye for any eye and tooth for a tooth', but certainly some sort of seed has been sown. If it was a seed that gave pain and sorrow then the fruit that I receive in turn will be bitter.
The time period between the performing of an action and the resultant reaction is variable. Just as different seeds need different periods of time in which to germinate, to grow and to produce fruit, so one cannot always determine which action it was that has led to this particular reaction but certainly if I am seeing a reaction, an effect, there must be a cause and the cause is not an external cause. The cause is I myself. In any situation that I find myself, nobody else, absolutely nobody else is responsible; it is I. It seems to be a very bitter law sometimes, in that it is the one that is absolutely inescapable.
An understanding of the law of Karma teaches us how to do pure action; we can then guarantee that, for the future, reactions will always be good, powerful and positive. It is possible to have a pill that can cure sickness for all time and that is the pill of Karma.