Organon §134

Different symptoms of a medicine appear in different provers and in different tests with the same prover.

All external potences, preeminently medicines, bring forth a particular kind of alteration in the condition of the living organism, each in its own peculiar way. However, all the symptoms belonging to a given medicine do not appear in one person, nor all at once, nor in the same experiment. When one person takes the substance in three different experiments, some symptoms may appear in the first experiment and others in the second or third. Other people may experience different sets of symptoms, however, in such a manner that some or several of the befallments that take place with the fourth, eighth or tenth person may already have appeared with the second, sixth or ninth person, etc. Also, symptoms do not appear at the same hour every time.