Homeopathic remedies work fastest and safest if they are as similar as possible to the diseased individual.
The law of similarity has existed long before homeopathy began, as can be seen from the following examples:
Paracelsus (1493 - 1541)
"Only the poison is also the cure"
Hippocrates (460 - 377 BC)
"Most diseases are curable by the very same factors as those from which they originate."