This section is from the book "A Compend Of The Principles Of Homoeopathy", by William Boericke. Also available from Amazon: A Compend of the Principles of Homoeopathy as Taught by Hahnemann.
The greatest minuteness and accuracy should be observed. A sensation should be described by some familiar comparison. State how the symptom is effected by different circumstances, i. e., the drug's modalities, as position of body, motion, rest, eating, fasting, day, night, indoors, open air, weather, etc. No circumstance, however trifling, should be omitted which may in any way tend to indicate the characteristic action of the drug and so precisionize it. All such conditions of aggravation and amelioration should be carefully recorded as they express the drug's individuality most clearly and universally.
The sides of the body on which symptoms occur should always be stated, many remedies acting more markedly on one side than another.
The times of occurence, aggravation or amelioration, are also very important, some remedies having distinctive morning aggravation of some or all of their symptoms, others at night, etc. As an illustration of a perfect description of a symptom, take the following of Hahnemann's proving of Nux: "Headache beginning some hours before dinner, increased after eating, then violent shooting pain in left temple, with nausea and very acid vomiting, all of which symptoms disappeared on lying down".
The three essential features of every complete symptom are, therefore,
(3) Condition of aggravation or amelioration (modality), which is the most important, and it ought to be the aim of all provers to observe symptoms with these features well in mind.
Never separate symptoms that appear in groups or with marked concomitants. Hahnemann always left together symptoms appearing in groups, if he considered them really connected; for instance, he observed, forty-five minutes after taking Pulsatilla, a cramp in the legs, in the evening, after lying down, with a chill; and at another time, in the evening, an aching, drawing pain in the legs up into the knee, with more chilliness than during the day.