From the excellent Twelve Principles of Buddhism, an appendix to Mahayana Buddhism, by Beatrice Lane Suzuki (the wife of D.T. Suzuki). The twelve principles were drafted by the London Buddhist Society early in the 20th century:

(4) The Universe is the expression of the law. All effects have causes, and man's soul or character is the sum total of his previous thoughts and acts. Karma, meaning action-reaction, governs all existence, and man is the sole creator of his circumstances and his reaction to them, his future condition, and his final destiny. By right thought and action he can gradually purify his inner nature, and so by self-realization attain in time liberation from rebirth. The process covers great periods of time, involving life after life on earth, but ultimately every form of life will reach enlightenment.

There are no miracles; everything arises because of understandable causes. It is a painful idea, perhaps, since we are solely responsible for our circumstances. But hopeful in that we can better our state simply by willing it and following through with the proper effort. We are at the mercy of no one.