Experiencing One or Oneness is very interesting, because it does not have a label. It does not have "units," or a "qualifier," such as One God, One World, or One Field, because, while you are experiencing it, it is all there is.
It is only when we come out of the experience that we can talk about it and qualify it and compare it to other experiences like it.
So... after experiencing one, naturally you want to know what things are Two, Three, etc. This is the basic organizing method of the material of rest of this site.