To the Greek philosopher Empedocles all the structure of the world could be explained by the presence of four "roots":
Fire, Water, Air and Earth
Later, Plato coined the term "elements" for these states of matter believed to be fundamental of what makes up the universe.
Of course, we have come to know that these configurations of atoms are not elementary in any physical sense, not even clearly definable substances, but the deeply-rooted cultural notion of some kind of basic, pure or natural state of things is still very powerful.