Moving force and stopping force, dissolving force and curdling force, pulling force and releasing force, joining force and separating force, work actively in the universe to sustain life and the Earth. This is also true within ourselves, as we are part of the universe and have a universe within our bodies. I believe this is much easier to understand than the definitions given by O sensei. Fire and water are two basic examples of the opposing powers. Fire naturally flows vertically, while water flows horizontally.
Water puts out fire, and fire evaporates water.
Many people ask about Aikido with relation to religion. I don t believe in religions because I know that history has seen a lot of conflicts among religions which have caused many great battles. Instead I believe in the god of fire and the god of water. It is such a simple concept that I wish people all over the world could come to support the idea. The final set of contrastive powers is positive and negative.