Homeopathy began with a German physician named Samuel Hahnemann in the late 1700s. At the time, common medical practices included bloodletting, purging, and the use of toxic substances like mercury. Hahnemann grew disillusioned with these methods, finding them crude and often more harmful than helpful. He believed there had to be a gentler, more effective way to treat illness.

His search for a new approach led him to experiment on himself. While translating a medical text, he read that cinchona bark, a source of quinine, was effective for treating malaria because of its bitter properties. Hahnemann was skeptical. To investigate, he took doses of cinchona bark himself. Though perfectly healthy, he began to develop symptoms strikingly similar to those of malaria: fever, chills, and joint pain. When he stopped taking the bark, the symptoms vanished.

This experiment sparked a revolutionary idea. What if a substance that produces certain symptoms in a healthy person could be used to cure those same symptoms in a sick person?

This observation became the first and most important principle of homeopathy: similia similibus curentur, a Latin phrase meaning “let like be cured by like.”

The core idea is that a substance capable of causing a set of symptoms can, in a specially prepared form, stimulate the body's own healing response to overcome a similar set of symptoms from an actual illness. An example often used is the onion. Slicing an onion can make your eyes water and your nose run. According to the principle of similars, a homeopathic remedy made from onion might be used to treat a person with hay fever who has similar symptoms of watery eyes and a runny nose.

Hahnemann and his followers began testing hundreds of substances on healthy volunteers, a process they called “provings.” They meticulously recorded all the physical, mental, and emotional symptoms each substance produced. These records, known as a materia medica, became the reference guides for matching a patient’s symptoms to the right remedy.

Hahnemann was working with potentially toxic materials, like arsenic and belladonna. To use them safely, he started diluting them. He developed a specific process of diluting a substance in alcohol or water and shaking it vigorously at each step.

Through his experiments, he came to a surprising conclusion. He believed that the more a substance was diluted and shaken, the more potent its healing effect became, while its harmful side effects disappeared. This led to the second major principle of homeopathy: the law of minimum dose. It states that the lowest possible dose of a medication should be used to achieve a healing response.

These two principles, 'like cures like' and the 'law of minimum dose', form the foundation of homeopathy. They represent a complete departure from conventional medicine, focusing on individual symptoms and the use of highly diluted substances to stimulate the body’s healing capacity.