In the case of acupuncture, the time period must also be considered. On a fine day, the sun shining, blood in the human body flows smoothly, saliva is free, breathing is easy. On days of chill and cloud, blood flows thick and slow, breathing is heavy, saliva is viscous. When the moon is waxing, blood and breath are full. When the moon wanes, blood and breath wane. Therefore acupuncture should be used only on fair warm days, when the moon is waxing or, best of all, when the moon is full.' 'Interesting,' Grace said in a comment, 'in bioclimatic research in the West, coronary attacks increase in frequency on cold chilly days when the sun is under clouds.' Dr Tseng turned the page of his blue cloth-covered book. 'Ah, doubtless the barbarians across the four seas have heard of our learning,' he observed without interest.