After years of practical experience with homoeopathy, Hahnemann found that certain chronic diseases could not be healed homoeopathically. During twelve years, he thus scrupulously researched and compared the medical histories of his patients and their family members and found connections between the seemingly most different symptoms. He thus concluded that a basic weakness makes certain people prone to certain diseases. According to his theory, these chronic diseases were based on a “miasm”, meaning as much as “contamination, defilement” in Greek.
Hahnemann defined three miasm which he called psora, sykose and syphilinie. He related psora (Greek for itch) to scabies, sykose to suppressed tripper and syphilinie to suppressed syphilis. He identified psora as the “original malady”, the mother of all miasm and basic cause of all acute and chronic diseases. Temporarily, a fourth miasm was cited; tuberculinie as a consequence of suppressed tuberculosis. Tuberculinie is a combination of psora and syphilinie.
More than 200 years ago and without today’s knowledge of genetics, Hahnemann thus realised that each person had a disposition for certain complexes of symptoms that are being passed from one generation to the next. He thereby is not talking about names of diseases, but about the symptoms: accordingly, e.g. the inclination for tumours may be passed on (sykose) or the disposition for diseases that include structural corrosion (syphiline).
Today, research has made enough progress to confirm Hahnemann’s thoughts. Skin rashes that are suppressed e.g. by cortisone or zinc can wander within the body and gradually cause neurodermatitis, bronchial asthma or allergies. On the outside, these are different diseases, but they all belong to the so-called atopic spectrum disorder and can alternate between each other. In the theory of miasmas this can mean that e.g. a child can develop hay fever if one of its parents has a severe skin allergy; it has the disposition for it and a weakening of its vital force is enough for the hay fever to suddenly break out.
The studies of drugs include the studies of the miasm. Each homoeopathic drug has different characteristics according to the various miasm. The homoeopath has to determine the active and the latent miasm of his patient and consider them in his choice of homoeopathic drug.
For further information I recommend Dr. Mohinder Singh Jus‘ easily comprehensible book „The journey of a disease“, B. Jain Publishing, ISBN 978-8131909300.