This article cannot define in the final analysis what tarot is or why it works. You will have to come to those conclusions yourself. You will have to find your own answers and find your own personal evidence probably through your success with the cards. It should be remembered also that we do not really understand the human mind. We do not understand why at Brown University, in blindsight experiments, people who are totally blind, can still tell when a light is shined into their face, whether it is vertical or horizontal.
Scientists just shake their heads and say it is some vestigal ability.
Look up the studies under blindsight in any book of psychology or here on the web and know that tarot is one such mystery. One of the most basic forms of layout for a tarot reading is past, present, future. You lay out three cards after shuffling, using a regular deck of cards and then place three cards in a row. The first card represents the past, or can in some case represent the subject or person or main idea of what you are asking about. The second card represents the immediate present and the third card usually represents the immediate future.