All of the elements. It is the same as the reality that you experience.

A smell, a sense, a thought, a dream, a premonition. All the same sense, interpreted differently depending on the geometry of relationships.

A man standing in a dark corner will appear differently than the same man standing in an open field next to a giant dragon in the daytime, or on the side of a building.

One thing, re-interpreted endlessly. There's only one force (the missing element, "nothing") that is first interpreted into something via relationships (the four elements). However, the four elements are all the same. The separation betwixt thought, dream, and reality are illusions. When we perceive them as being separate we are simply perceiving what would be called a time-space lapse between values in perspective. (Derivative values of the 4 elements.)

A premonition has symbology, interacts, works in potential energy, and has logic. It can be interpreted in any way with varied results.

Apologies for the above not being that clear.