The past effects the present by important people doing important things that change for the better. (or the worse!) When lots of things happen at once the future can be changed from the actions of a few people. Small things can have a big impact on the world. For example, if Cortez did not lead the Spanish Conquest against the Aztec, Maya, and Inca , they would still be roaming around today. Also, if the ancient American civilizations did not discover farming, we would still be hunting and gathering today.