In the conventional approach to treating disease a drug is prescribed to treat the presenting symptoms. Hence a painkiller is prescribed for pain; an antidepressant for depression. We are accustomed to the idea of treating symptoms this way.
Homeopathy on the other hand regards the symptoms as signs of the person's healing responses endeavouring to restore health and balance. for example, in a case of food poisoning the symptoms of diarrhoea and vomiting are obviously the body's way of ridding itself of toxic substances before they can do damage. This principle applies even in cases of chronic diseases such as arthritis or migraine. Although the body is unable to overcome the problem fully, we still understand the symptoms to be the effort to keep the conditions as tolerable as possible.
This explains the use of 'similars', substances which when given to a healthy person will create similar symptoms to the ones being treated. Therefore when treating hay fever with symptoms of sore, itchy, watery eyes and a runny nose, Allium Cepa, or common onion is prescribed because of its ability to induce those symptoms in everyone. In this way the natural inclinations of the body towards its own recovery is encouraged by the prescription of the similar homeopathic remedy and an improvement results.
In order to make this treatment totally safe the remedies are diluted to infinitesimally small levels. These dynamic potencies only meet an answering response if they are appropriate and curative. This response is a gentle permanent recovery back to health.