There can be no first cause of reality. If there was a first cause. It could only be every cause existing in an infinite chain of causes and effects. The effect would have to be the cause. And all those causes and effects would not be able to differ from the original cause. That is because nothing could be taken away or added to the original cause as it would be the only thing that could possibly exist. This means that you cannot define or conclude a cause or effect for anything as it will continually elude your intelligence.