In fact, the simillimum is practically never found among the diagnostic symptoms. In considering the diagnostic symptoms in the selection of the remedy, its only practical value is in excluding those remedies from consideration, which do not correspond to the genius of the disease, but act chiefly on other parts of the organism. 
In considering the value of symptoms there are certain symptoms that are apparently caused by conditions, and that almost precede the symptomatology, and seem to give a basis for the patientís condition. These may be exposure to cold; exposure to wet; all those conditions of which people say that thus and so was the cause of their illness and the cause of their symptoms. These play a large part in pathological prescribing. In pathological prescribing these causes of disease loom large; in homeopathic prescribing they do not loom as large, save as showing the tendencies of the patient. 
You will learn so much about the purport and the aspect of every motion of the human being that you will place less and less reliance on diagnostic symptoms as diagnostic symptoms, and learn more the value of symptoms as symptoms. Y ou will be astonished to find how expert you will become about diagnosis and prognosis by studying the symptoms. 
A true homeopathic prescription cannot be made on pathology, on morbid anatomy; because provings have never been pushed in that direction. 
1. Roberts, Herbert A., M.D., The Principles and Art of Cure by Homeopathy.
2. Kent, James Tyler, M.D., Lectures on Homeopathic Philosophy