Lama Zopa Rinpoche
Karma is in the category of mind. Karma is not substantial; it is a formless phenomenon. If the mind is formless whereas the body is form, how can the formless imprints determine something physical like our bodies? This is very simple. Our own daily experiences give us the answer.
Think about what happens when we are angry. The anger definitely produces physical effects and changes in our body. It is the same when we have strong attachment or strong pride. And because of these changes in us, others are affected. Think of the changes that occur in us and in the people around us at times of really strong fury.
Basically it is the same as when an architect designs something. The building is first there only in his imagination, then it becomes plans and then it is actualized.
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Karma is intention
Karma can be defined as intention (Tib: sem-pa). It can be explained as the action of the principal consciousness. "Karma" is a Sanskrit term that simply means action, so it is an action of the thought.
Before any act there must be a motivation, an intention, otherwise there would be no energy for the mind to act. That is the motivation of cause. But even during the act there is still some motivating energy and that is the motivation of time. Both are karma.
The first one, the motivation of cause, gets us to initiate the action, like before we meditate the wish to meditate arises. While the action is actually happening, there still needs to be an accompanying motivation, otherwise the action would never be completed, and that intention is called the motivation of time.
These two motivations exist in any action—reciting mantras, reading sadhanas, even mundane actions like walking, sitting, sleeping and so on. There is the intention than initiates the action, the motivation of cause, and the intention that causes the action to continue and be completed, the motivation of time.
Therefore we need to ensure that we not only have the best possible motivation before we do the action—the motivation of cause—but also while we are doing it—the motivation of time—so that the action is as pure as possible. That way, what we do becomes very powerfully positive karma.
Therefore it is important to check not just before we act but while we are acting. Otherwise, for instance with an act of charity, we can generate a very positive motivation before the act, but while we are doing that action the mind can degenerate into wanting recognition and thanks or some other negative thought. Then we have still created good karma with our initial motivation, but the motivation of time is negative karma and so the action is not completely perfect.
