Mind and soul are classified only in duality. In non-dual reality there is neither soul nor mind , everything is one. Therefore soul and mind are one in essence, that is consciousness. universe is mind because when the mind is present the universe is present, and when the mind is absent then the universe absent.
Samadhi is natural state of the true soul,which is in the form of consciousness. In natural state the universe or mind is nonexistent. And in duality/mind the universe is present. Thus the duality and non duality is state of the self, not some theory. The whole objective awareness is created out of one formless substance, and that formless substance itself is the witness of the dual and non-dual experiences which appear and disappear as
Until one becomes aware of the formless substance and witness of the duality, he experiences the duality as reality. Thus it is very much necessary to realize the fact that there is no second thing exits, other then Atman (consciousness or spirit), in the experience of diversity/duality, to bring unity in diversity.