So, if you think everything you observe must be there for some reason---every effect has a cause---then you want to know the reason, the cause. How will you think about maggots on rotten meat, appearing to have come from nowhere? Maybe you will think of some version of spontaneous generation. Or, if you're more scientifically minded, you'll think of a way to figure out some other way that those maggots got there.
(I'd like to write more about the ancients' beliefs in spontaneous generation, but I'm not a scholar of the Greek or Roman languages and history, and all I know about it is what I've read online. For anyone else who is interested, I recommend the Wikipedia article about spontaneous generation. That's all I know about it. But I must say that from this article it looks to me like these ancient Greeks were really poets, not scientists, as in this quote: "Anaximander of Miletus considered that from warmed up water and earth
emerged either fish or entirely fishlike animals. Inside these animals,
men took form and embryos were held prisoners until puberty; only then,
after these animals burst open, could men and women come out, now able
to feed themselves.")
(Or you could read the Britannica article on spontaneous generation, which gives the example of how ancient people even thought mice were spontaneously generated from pieces of cheese and bread wrapped in rags and left in a corner.)
Back to showing how maggots and worms and even mice don't just spontaneously generate from nothing: It took an Italian physician, Francisco Redi, in 1668, to show that dead meat doesn't just produce maggots spontaneously: He filled six jars with decaying meat: three sealed jars, and three open to the air. Flies got into the unsealed jars and laid eggs on the meat, out of which came the maggots. Not everyone was convinced, some people saying it was a lack of fresh air that kept the maggots from appearing spontaneously in the three open jars. So, in a second experiment, Redi covered the tops of three of the jars with a fine net, so air (but not flies) could get in. And, again, no maggots appeared on the meat in those jars.
More on the topic here: Still not everyone was convinced, though. Anton van Leewenhoek invented a microscope, through which he saw tiny, fast-moving "animalcules" that he'd found in rain water. Where did they come from? Spontaneous generation? He thought so: they appeared in this water to which he had added scrapings from his teeth, even though these animalcules didn't show up after he had drunk hot coffee. (This is not a plug for coffee, in any form!)
It took Louis Pasteur, in the mid-19th Century, to show that "microorganisms, organisms too small to be seen except through a microscope," can reproduce and cause fermentation, and also cause decay and putrefaction in wounds. I should mention that Joseph Lister and Robert Koch also studied, and contributed to the acceptance of, the germ theory.
Next: Where are we going with this?