§251
There are some medicines (e.g., ignatia, also bryonia and rhus, and sometimes belladonna) whose power of altering man’s health consists chiefly in alternating actions – a kind of primary-action symptoms that are in part opposed to each other. Should the practitioner find, on prescribing one of these, selected on strict homoeopathic principles, that no improvement follows, he will in most cases soon effect his object by giving (in acute diseases, even within a few hours) a fresh and equally small dose of the same medicine.1
1 As I have more particularly described in the introduction to Ignatia (in the first volume of the Materia Medica Pura).