Thus became the beginnings of the first law of homeopathy: like heals like. This means that whatever symptoms a substance produces in its gross/original form, it can cure that set of symptoms when the substance is diluted into a homeopathic medicine. It is so diluted that the final preparation is completely nontoxic and safe. 

Let me give you an example: Let’s think of an onion. What symptoms does it produce in its gross/original form? In other words, what happens when you chop an onion? Or what symptoms would you experience if you perhaps bit into an onion?

If your response is watery eyes, egg-white runny nose, burning eyes/nose, and perhaps even sneezing, then you are correct! Now what illness produces those symptoms? Seasonal allergies? The common cold? Right again!

So the homeopathic remedy made from onion can actually cure those types of colds and allergies which produce the similar symptoms an onion produces. Note that in homeopathy we don’t use the common name of the substance. So instead of calling this remedy “homeopathic onion,” we instead name it by its latin name. So onion is named Allium cepa.

And there you have it. You just learned the first law of homeopathy.