"Element" is a fairly general word, we just generally use it colloquially to refer specifically to the chemical elements. If you interpret his usage in the same way we use "states of matter", it's not horrendously far off. Earth, water, air, and fire roughly correspond to solid, liquid, gas, and (extremely rudimentary, very low ionization) plasma (or perhaps a more general energetic concept). In any case, an object "wanting" to get to its "natural" place also isn't terribly far off from a statement of consistent physical laws. Solids do "want" to accumulate with other solids by gravity, energetic gases do "want" to rise above less energetic ones through buoyancy.