"Empedocles also said that you saw colours because different types of light entered your eye. He thought light was very important, and that the velocity of light was one of the most fundamental things of all. He thought that sound was a pulsation in matter, and showed that air is such matter, by showing that if a cup is inverted over water, the water that goes in is equal in volume to the air permitted to escape.
"He also showed something you can see for yourself later. If you put a lodestone under a parchment, and put on iron dust, which I have got here from the sword sharpeners, you will see lines. Empedocles argued that one end was attracted to the other and a flow of something was going around to the other end. It is repulsed, however, by itself. You can see this for yourself with this small collection of lodestones. Hold them close together, then rotate one. Now, take these lodestones, and take the iron dust, and see for yourself. See if you can come up with a conclusion."
Lodestones! Yes, Athene had mentioned them, and he was supposed to find something significant about them. But how? He recalled that Athene had said he must note what he found, not that as yet he had found anything. He moved the lodestones, felt an attraction, so he let the two join together, at which point he noted the lines of iron filings were a larger version of what one lodestone would give. He turned one lodestone around and noticed that they now repulsed each other, but the force was not strong so he could leave them in place, at which point he saw the lines of filings behave as if the lines were pushing against each other.
So, something was going out one end and going in the other. If that were the cause of the repulsion, then the repulsion should be stronger between one pair of ends than the other pair. Yes, he could find that. The only problem was, when he tried it, both pairs of repelling ends behaved more or less that same. Something to note: a wrong idea!
Why did the iron filings line up? Other dust did not, but the filings lined up similar to how tiny pieces of lodestone did. Perhaps the iron was taking up that property? He got a small nail, and began rubbing one of the lodestones along it, and after some time, it too would align iron filings, albeit weakly. Yes, the reason why the lodestones pointed north! They were lining up like the iron filings. The middle of the Earth must be either a massive lodestone, or maybe a massive lump of iron. Not that he could ever prove that.
It was then that he thought some more, moved the lodestones again, and found that the lines never crossed. Something to note that worked! What about numbers of lines? They seemed to be the same for a given lodestone, but ones that seemed to be stronger seemed to give more lines. He thought about this a little more, then he started to count the lines emanating from a lodestone, and he wrote down the numbers. He then fixed one of the stronger lodestones into a piece of wood, then he tied another onto a piece of string and lowered it down towards the other so that the ends attracted. By moving the support, he could make the force of attraction swing the stringed lodestone like a pendulum and measure how high he could get it to lift for a given distance between lodestones. As he suspected the angle he could make it move was much higher the shorter the distance. He made some measurements then changed lodestones, and repeated the experiment, intending to correlate his distances with the number of lines he had counted. There would be a constant weight towards the centre of the Earth for each lodestone, so what he was measuring was the force between them countering that weight. Later he would do some calculations. But then what? Show what he worked out to no person?
It was then he had another idea. He remembered his amber that attracted hair and very light pieces of dust. He got his pieces out again and rubbed vigorously, and yes, the fur seemed attracted to the amber in lines. He got two charged up and suspended them, and yes, they repelled each other, but when he tried to turn them around, the repulsion stayed, except that with his fiddling, the repulsion lowered, no matter what he did. The rubbed amber was like the lodestone in some ways, but not in others. What did that mean? He did some more experiments, writing down what he did, but at the end he seemed more confused.
* * *
Gaius expected Timothy to ask him about lodestones, but to his surprise, he did not. Obviously, Timothy had forgotten. Actually, Timothy had not. He had seen Gaius with his lodestone suspended from a string, while moving a piece of wood towards it, then making measurements. He had later seen Gaius doing some rather awkward calculations, and he had no intention of being drawn into those. As far as Timothy was concerned, there was to be no further discussion of lodestones. Still, if Gaius was so intent on mathematics, he could easily divert his attention.
"Today we recall Pythagoras argued that everything is underpinned by numbers. Plato applied this to Empedocles' elements, and noted that there are five regular shapes with faces, or six if you consider a sphere to have one face. There is the tetrahedron, the cube, the octahedron, the dodecahedron and the icosahedron. Now, Plato thought about this. Do you notice a connection with the number five?"
"It follows four and precedes six?"
"That's not exactly what I mean. Some Greeks," and he emphasized the word some, "have noticed that there are five elements, seven metals, and five planets."
Yes, Gaius thought to himself, if there were a record for the most tendentious nonsense in the world, this would be it.
"It all follows from the fundamental importance of symmetry. The primitive matter is represented by a circle, the most symmetric of shapes. Such matter is worked on by two properties: hotness and its contrary coldness, and dryness and its contrary, wetness, such that opposites have nothing in common. Thus on opposite sides are fire and water, air and earth, while the properties can be shared by adjacent elements, thus fire and air can share hotness, air and water wetness, and so on."
"According to this," Gaius frowned, "you can't heat water. That must be wrong."
"Not at all," Timothy said in a firm tone. "Fire can heat earth, and hot earth makes water hot. You have to place your water in a pot, or it puts out fire. That's a fine example of the symmetry at work."
"Perhaps, but you can explain anything like that," Gaius shrugged disparagingly.
"Because it's a fundamental truth!" Timothy snorted. "Of course substances may be mixtures of the ideal elements. Suppose I put a pot of seawater on a fire. If the real fire contains some earth, the bottom of the pot becomes black. The seawater is a mixture of water and earth, so when water is driven off you get wet air and leave behind dry earth. The underlying material has had its properties changed, which changes the elements."
"Changes the elements? You mean, things aren't made of unchanging elements."
"Not according to Aristotle," Timothy smiled. "The elements are states, and the change of elements changes the state of being. When burning wood, wood does not combine with fire or anything else. Instead, fire is an agent of change and is coming into being while the wood is passing away. Water has the property of wetness, but so does oil; fire cannot come into being from water, though, but it can from oil, so oil is not a fundamental element of change, but is changed itself by the element fire, which liberates air and perhaps a little earth from the oil."
"Why does oil have air rather than water? Because of fire?" Here was a theory that explained everything and nothing both at the same time!
"Oil has air and water," Timothy stated. "It has wetness, but yes, the fire shows it has air. Also, elements tend to separate and go to their natural place, determined by the contraries up and down. Fire, being like the heavens, goes up strongly, while earth, being the heaviest, and most earth-like, falls fastest. Water falls slowly, air rises slowly. Oil sits on the top of water, so obviously it has more of the nature of air."