Homeopathy as we know it today dates back over 150 years and really was the original alternative medicine as it was developed as a direct result of the harmful medical practices of the time.It was a German medical doctor called Samuel Hahnemann (1755-1843) who became very disillusioned and appalled with the harmful medical practices of his day, which included bloodletting, leaches and the administration of what we now know to be incredibly harmful substances such as lead and mercury. It was Hahnemann's frustration with this that led to the development of Homeopathy.
It was Hahnemann who proved the main principle of Homeopathy, which is 'like cures like' (i.e. a substance which causes symptoms and disease in a healthy person can be used to cure those same symptoms in a unwell person suffering from the same types of symptoms).He came about with this theory after experimenting with the substance Quinine, which at the time was an effective treatment for malaria. He realised that after taking doses of Quinine he started to develop malarial symptoms, despite not having malaria.
From this, he went on to experiment with many other substances and record their effects in humans, this is a process known as 'homeopathic proving'. By observing the symptoms any substance produced when given to a healthy person, Hahnemann could discover the healing properties of that substance. There are now more than 2000 remedies that have been 'proved' although only a small amount of these are frequently used in practice.