Rotting Grass Transforms into Fireflies: The Philosophy of Metamorphosis and the Earth Virtue of Late Summer in the Great Heat
This article offers a deep reading of Great Heat (Dashu), the twelfth of the twenty-four solar terms, through the lenses of pre-Qin Confucian and Daoist philosophy, classical etymology, and astronomical phenology. It reveals the cosmic significance of the sun reaching ecliptic longitude 120°, when summer heat attains its zenith, and explores the Earth virtue of late summer, the metamorphosis of rotting grass into fireflies, and the hexagram Dun with its two rising yin lines — illuminating the ancient wisdom of reversal at the extreme and counterbalancing excess.
Chapter Fourteen: Rites and Folk Customs of Great Heat — Dog Days and Sending Off the Heat
I. Welcoming-the-Energy Rites: The Dual Sacrifices of Late Summer and Central Earth
Because late summer belongs both to "summer" (Fire, the south) and to "Central Earth," the ritual arrangements for the month of late summer reflect this duality. On one hand, late summer continues the summer tradition of sacrificing to the Fire virtue (the Flame Emperor, Zhurong); on the other, "Central Earth" — as an independent "fifth season" — calls for sacrifice to the Yellow Emperor and Houtu at the zhongliu (the central skylight of the dwelling).
II. Dog Days: Pre-Qin Rites of Heat-Avoidance and Disaster-Aversion
Whether "warding off pestilence with dogs" or "closing doors to avoid spirits," Dog Days rites were essentially the ancients' wisdom for coping with the fierce heat and epidemic-prone conditions of midsummer — combining practical measures (heat avoidance, physical nourishment) with devotional acts (sacrifice, spirit-aversion).
III. Tasting the First Fruits and Offering Sacrifices: Honoring Heaven with New Grain
As late summer approaches, early rice and other crops gradually ripen, giving rise to the custom of "tasting the first fruits" — savoring newly harvested grain and offering it in sacrifice to ancestors and deities. This custom embodies the Confucian principle of "repaying the root and returning to the beginning" (baoben fanshi) — the Book of Rites says: "All things have their root in Heaven; all people have their root in their ancestors." The late-summer "offering of first fruits" is an act of profound gratitude at the moment when the crops, nurtured by late summer's Earth virtue, have first come to fruition — gratitude to the heaven and earth that nurture all things, and to the ancestors who sustain the lineage.
IV. Sending Off the Great Heat Ship: A Living Relic of Disaster-Aversion Custom
In later folk practice (especially along the southeastern coast), Great Heat sees the custom of "sending off the Great Heat ship" — communities build an elaborate vessel, load it with offerings, hold a grand ceremony, and send the ship out to sea (or burn it) to drive away the summer heat and pestilence and pray for peace and health.
Though a later custom, its spiritual core traces back to the ancient pre-Qin tradition of Dog Days "warding off pestilence." The thinking behind "sending off the Great Heat ship" — materializing an abstract threat (summer toxins, epidemic energy) into a concrete object that can be ritually dispatched — is a relic of archaic shamanic exorcism. It reflects the ancients' complex attitude when facing the overwhelming forces of nature: awe and reverence combined with resistance and the will to prevail.