This is not the place in which to enter on an exhaustive inquiry as to the nature of causation. It is enough to point out that the whole theistic fallacy rests here on the assumption that we are dealing with two things, when as a matter of fact we are dealing with only one. Cause and effect are not two separate things, they are the same thing viewed under two different aspects. When, for example, I ask for the cause of gunpowder and am told that it is sulphur, charcoal, and nitre, or for a cause of sulphuric acid and am given sulphide of iron and oxygen, it is clear that considered separately these ingredients are not causes at all. Whether charcoal and sulphur will become part of the cause of gunpowder or not will depend upon the presence of the third agent; whether sulphide of iron will rank as part of the cause of sulphuric acid will depend upon the presence of oxygen. In every case it is the assemblage of appropriate factors that constitute a real cause. But given the factors, gunpowder does not follow their assemblage, it is their assemblage that is expressed by the result. There is no succession in time, the result is instantaneous with the assemblage of the factors. The effect is the registration, so to speak, of the combination of the factors. Now if what has been said be admitted as correct the argument for the existence of God as based upon the fact of causation breaks down completely. If cause and effect are the expressions of a relation, and if they are not two things, but only one, under two aspects, "cause" being the name for the related powers of the factors, and "effect" the name for their assemblage, to talk, as does the theist, of working back along the chain of causes until we reach God, is nonsense. Even if we could achieve this feat of regression, we could not reach by this means a God distinct from the universe. For, as discovering the cause of any effect means no more than analysing an effect into its factors, the problem would ultimately be that of dealing with the question of how something already existing transformed itself into the existing universe. A form of a very doubtful Pantheism might be reached in this way, but not theism. But here a fresh difficulty presents itself to the theist. A cause, as I have pointed out, must consist of at least two factors or two forces. This is absolutely indispensable. But assuming that we have got back to a point prior to the existence of the universe, we have on the theistic theory, not two factors, but only one. The essential condition for an act of causation is lacking. A single factor could only repeat itself. By this method the theist might reach "God." But having got there, there he would remain. He is left with God and nothing else, and with no possibility of reaching anything else.