Classical Greek

The Greeks are considered the fountain of Western thought. They believed, even before Socrates, that all things were composed of Four Elements: Air, Water, Fire and Earth. Aristotle added a fifth essence called Aether (pronounced ether), which he thought made up the heavenly realms. Actually, the Eastern philosophers came up with systems not so different from this and can be compared (Wikipedia HERE, right column).

As early as the Middle Ages people started experimenting with various substances. Around the year 800, a Middle Eastern alchemist known as Geber (Latinized version of Jabir, Wikipedia HERE) discovered the separate elements of sulfur and mercury. In 1869, Dmitri Mendeleev presented a table of known elements which showed they have certain repeating properties. This "Periodic Table" is still used to classify elements. It starts with Hydrogen, which has one proton and one electron, and as of June 2009 includes 117 elements. Other elements include carbon, nitrogen and oxygen.

Therefore, we have a replacement of Aristotle's elements with those we know today through scientific research. I've also read that Aristotle believed one could discover science through logic, not experiment. The example I read a long time ago was that he proclaimed how many teeth a horse has without looking into the horse's mouth. Later someone actually counted them and found Aristotle was wrong. I don't have a reference for this story and it may be a fable, but it does illustrate the general idea.

Though Aristotle knew about magnetism, Hans Christian Orsted in 1820 realized magnetism could be generated by an electrical charge flowing through wire. This eventually led, through others, to the understanding of electromagnetic radiation. This energy is one of the basic forces of the universe, along with gravity and the strong and weak nuclear forces. The understanding of natural physical forces has replaced, in the opinion of many, the understanding of causes as Aristotle described it in his theory of Universals. (A universal is a quality which exists in itself that is seen in physical things, for example, "red-ness" of red things and "human-ness" of humans.) Aristotle said there were "Potentials" of existence which a First Mover would have had to put in motion in order to get something to exist in matter and form.

There is an interesting entry on "Theodicy" HERE on the New Advent website in their 1917 Catholic Encyclopedia. This older version of the encyclopedia can be helpful in historical matters and general definitions. Theodicy is the attempt to prove God through natural means. You may like to read the information on it at the link above.