If a lotus flower comes, there will be a reflection of lotus flower in the mirror. According to the subject, the reflection will be changed. A bean sprout comes from a bean. This is Karma. Everybody makes his condition by his thought and actions.
Bad karma comes from bad action.
Without cause we can not get any effects. That is Karma. The Hell Bodhisattva said one time. Karma is so strong, it is as high as the Sumi mountain, as deep as the ocean, it is an obstacle in the way to be Buddha. So we should keep in mind clearly and should not neglect little sins.