The nature of the disease, the age and constitution of the patient, as we have said, complete our group of reasons for determining the choice of the dilution.
Although this proposition evidently implies two distinct points, we shall, for the sake of abridging it, treat it without observing this distinction. It may, beside, be summed up in a single principle, a principle based upon observation, and of which the following is the statement :
The power of homeopathic medicines is in direct proportion to the vital activity of the subject, while the duration of their action is in inverse proportion to the same.
Whence we immediately draw the practical conclusions :
The younger and more vigorous the patient, the more acute, rapid and inflammatory the disease, and manifesting itself, as it were, by an increase of vitality, the more important it is to reduce the doses, while, at the same time, we lessen the intervals of their repetition.
For old people, on the contrary, as well as for emaciated or lymphatic subjects, of a low and feeble vitality, who are refractory or almost insensible to medicinal excitation, the lower dilutions are most appropriate.
In conclusion, to increase to a greater or less extent the intervals between the doses, in the treatment of chronic diseases, is a rigorous deduction from the principle we have just announced, and of which some general notions upon the nature of disease, developed in the following chapter, will perhaps better enable us to understand the bearing.