Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace.
While the genre of some works of literature can be debated, Macbeth written by William Shakespeare seems to fit into a perfect mold. Aristotleâs definition of a tragedy, combining seven elements that he believes make the genre of a work a tragedy, is that mold. Displaying all seven aspects, Macbeth fits the definition precisely. Key elements in the play substantiate the fact that Macbeth is a serious story, the first elements of Aristotleâs definition.
Aristotle proposed a fifth element, aether, in addition to the four proposed earlier by Empedocles. 1  Earth, which is cold and dry; this corresponds to the modern idea of a solid. 2  Water, which is cold and wet; this corresponds to the modern idea of a liquid. 3  Air, which is hot and wet; this corresponds to the modern idea of a gas.