<blockquote><p>He [Aristotle] refers to many examples of changes now constantly going on, and insists emphatically on the great results which they must produce in the lapse of ages. He instances particular cases of lakes that had dried up, and deserts that had at length become watered by rivers and fertilized. He points to the growth of the Nilotic delta since the time of Homer, to the shallowing of the [[Palus Maeotis]] within sixty years from his own time ... He alludes ... to the upheaving of one of the Eolian islands, previous to a volcanic eruption. The changes of the earth, he says, are so slow in comparison to the duration of our lives, that they are overlooked; and the migrations of people after great catastrophes, and their removal to other regions, cause the event to be forgotten.</p><p>He says [12th chapter of his ''Meteorics''] 'the distribution of land and sea in particular regions does not endure throughout all time, but it becomes sea in those parts where it was land, and again it becomes land where it was sea, and there is reason for thinking that these changes take place according to a certain system, and within a certain period.' The concluding observation is as follows: 'As time never fails, and the universe is eternal, neither the Tanais, nor the Nile, can have flowed for ever. The places where they rise were once dry, and there is a limit to their operations, but there is none to time. So also of all other rivers; they spring up and they perish; and the sea also continually deserts some lands and invades others The same tracts, therefore, of the earth are not some always sea, and others always continents, but every thing changes in the course of time.'<ref>[[wikiquote:Charles Lyell|Charles Lyell]], ''[http://books.google.com/books?id=mmIOAAAAQAAJ& Principles of Geology]'', 1832, p.17</ref></p></blockquote>
Aristotle proposed a fifth element, aether, in addition to the four proposed earlier by [[Empedocles]].