Intentional actions have the latent power within them to bear fruit in the future - either in a later part of the life in which they were performed, in the following life, or in some more distant life, but their potency is not lost with even the passing of aeons; and whenever the necessary conditions obtain that past kamma may bear fruit. Now, in past lives we have made kamma, and due to our ignorance of the Four Noble Truths we have been "world-upholders" and so making good and evil kamma we have ensured the continued experience of this world.