火性不同，皆可炊□□焚，今世取人，大约□□□□□□□□□□火也。其实火之资益，
关
于疾病寿夭□□□□□□□□□□火，非无意也。今人不讲者，以炉灶石火，取□□□□□
□□□□之法，谁知钻燧之火，有益于人不浅乎。我今阐发其义□□□君子采择焉。春宜取
榆柳之火，盖榆柳之气，得春气最早□□叶先百木而青，取其火以生春气，则一春无郁结之
病也。夏宜取枣杏之火，盖枣杏之气，得夏气最全，故其心纯赤，取其火以长夏气，则一夏
无吐泻之病也。秋宜取柞 之火，盖柞 之气，得秋气俱多，故其理皆白，取其火以收秋气
，则一秋无疟痢之病。冬宜取槐檀之木，盖槐檀之木，得冬气甚坚，□□□□□火以藏冬气
，则一冬无寒凛之病也。长夏宜取桑柘之□□□柘之木，得长夏和气，故其肌为黄，取其火
以合四时之□□□夏无湿热之病也。上古之人，无有 疾者，虽性情恬□□□□火之益也。
今世所用□灶之火，此传薪之□□□□□□□□未免杂而不纯，乌能却病哉。至于石中□□
□□□□□□□损，又不若传薪之火矣。夫延年即□□□□□□□□□□□以益寿哉，修仙
之士，专尚水火，可不留□□。
火的性质各不相同，都可以用来烧火做饭或焚烧物品，如今世人选取木材（作为燃料），大约是根据五行中“木生火”的道理来对应五季之火。其实，火对人体的滋养益处，关系到疾病的产生与寿命的长短，这并非没有道理。现在的人不讲求这一点，是因为炉灶中的石火，只是获取薪柴燃烧的方法，谁知道钻木取火这种原始的火，对人的益处并不浅呢。我现在阐发其中的义理，希望君子们能够采纳。
春季适宜选用榆树和柳树的木材生火，因为榆树和柳树的气息，最早得到春天的生气，它们的叶子比百木更早变青，选取它们的火来助长春气，那么整个春天就不会有气机郁结的疾病。夏季适宜选用枣树和杏树的木材生火，因为枣树和杏树的气息，完全得到了夏天的热气，所以它们的心是纯红色的，选取它们的火来助长夏气，那么整个夏天就不会有呕吐腹泻的疾病。秋季适宜选用柞树的木材生火，因为柞树的气息，大多得到了秋天的肃杀之气，所以它的纹理都是白色的，选取它们的火来收敛秋气，那么整个秋天就不会有疟疾和痢疾。冬季适宜选用槐树和檀香的木材，因为槐树和檀香的木质，得到了冬天的寒气而非常坚硬，选取它们的火来封藏冬气，那么整个冬天就不会有寒冷凛冽的疾病。
长夏（夏秋之交）适宜选用桑树和柘树的木材，因为桑树和柘树的木质，得到了长夏的平和之气，所以它们的肌理呈现黄色，选取它们的火来调和四时之气，那么整个长夏就不会有湿热的疾病。上古时期的人，没有各种疾病，虽然他们的性情恬淡安静，但也得益于火的益处。如今世人所用的炉灶之火，这是传递薪柴燃烧产生的火，其中难免混杂而不纯粹，怎么能去除疾病呢？至于石头中发出的火（如燧石打火），其损伤更大，又不如传递薪柴之火好了。那些延年益寿的方法，以及修仙之人，专门崇尚水火之道，怎能不留意呢。
The nature of fire varies, yet all can be used for cooking or burning. In contemporary times, the selection of wood for fuel is generally based on the principle that "Wood generates Fire," corresponding to the fires of the five seasons. In reality, the nourishing benefits of fire are closely related to the onset of diseases and longevity; this is not without reason. However, people today do not study this matter because they only view the fire from stoves and hearths as a method derived from burning firewood. Who would know that the fire obtained by drilling wood (drilling-fire) offers profound benefits to humans? I now elucidate its principles, hoping that gentlemen will adopt them.
In spring, it is appropriate to use firewood from elm and willow trees. The qi of these trees receives the spring qi earliest, and their leaves turn green before other trees. Using their fire to generate spring qi ensures that one will suffer no stagnation-related illnesses throughout the season. In summer, it is appropriate to use firewood from jujube and apricot trees. Their qi fully embodies the summer heat, and consequently, their hearts are purely red. Using their fire to promote summer qi prevents vomiting and diarrhea during the season. In autumn, it is appropriate to use firewood from oak trees. The qi of oak trees largely reflects the autumnal energy, and thus its grain is white. Using its fire to gather autumn qi prevents malaria and dysentery in autumn. In winter, it is appropriate to use wood from locust and sandalwood trees. These woods are very hard due to receiving the winter cold. Using their fire to store winter qi prevents illnesses caused by severe cold throughout the winter.
During the late summer (the transitional period between summer and autumn), it is appropriate to use wood from mulberry and zhe trees. These woods possess the harmonious qi of late summer, and their texture appears yellow. Using their fire to harmonize the qi of the four seasons prevents damp-heat illnesses during this period. People in ancient times did not suffer from various diseases; although their temperaments were tranquil and quiet, this was also attributable to the benefits of fire. The stove fire used by people today is merely the fire passed down from burning firewood; it inevitably contains impurities and cannot effectively dispel disease. Furthermore, fire struck from stones causes greater harm and is inferior to the fire from burning wood. Those who seek longevity and immortals who specifically revere water and fire should certainly pay attention to this.