"Human beings are susceptible to infection and contagion in various degrees. One man will become infected in contact with diseased individuals while another will experience no I'll effects whatever. One person is made ill by noxious plants while another man can handle them with impunity. Certain people are capable of making a wonderful proving of a drug, whereas others will show no reaction whatever. In analysing susceptibility, we find it is very largely an expression of a vacuum in the individual. This is illustrated by the desire for food. The vacuum attract s and pulls for the things most needed, that are on the same plane of vibration as the want in the body. Contagious diseases thrive in childhood because of the extreme susceptibility of the miasmatic influence;: this susceptibility has an attractive force which draws to itself the disease which is on the same plane of vibration and which tends to correct this miasmatic deficiency."
- Herbert A. Roberts, M. D
This types of vacuum cannot occur only in the molecular level of the body but also may occur in general systemic level, where the frequency of the vital principal may become deranged due to miasmatic influence.
"By susceptibility we mean the general quality or capability of the living organism of receiving impression; the power to react to stimuli. Susceptibility is one of the fundamental attributes of life. It is a well-known fact that the living organism is much more susceptible to homogeneous or similar stimuli then to heterogeneous or dissimilar stimuli. Susceptibility as a state may be increased, diminished or destroyed. Susceptibility in organism, mental or bodily, is equivalent to state. State involves the attitude of organisation to internal cause and to external circumstances."
-Stuart close, M. D
The Genius of homoeopath, page-76, edition 2002 reprint by B.Jain publishers.
"Susceptibility is an inherent capacity in all living things to react to stimuli in the environment and represents a fundamental quality that distinguishes the living from the none living. Susceptibility is made known to us through the reaction that results when the host meet the environmental factors. Any change in the normal susceptibility will interfere with the capacity of predetermined response and this interference will be reflected in a chains response which ultimately leads to a loss of balance as evidenced by the development of disease. "
Principles & practice of homoeopath, part 1,page no-243,edition-2000 reprinted by institute of clinical research.