Night deepened like a stick of ink repeatedly kneaded, slowly spreading across the ceiling of "The Nest," swallowing the last trace of steel-blue cold light into thick, velvety blackness. Those towering server cabinets, originally resembling lined-up behemoths breathing with the metallic sweetness of electric currents, now seemed to have been muted by an invisible hand, leaving only the faintest "tap—tap—" from the power supply modules, like the heartbeat of a dozing giant—distant, restrained, yet enough to remind one they could awaken at any moment. The air conditioning ducts still delivered a constant eighteen-degree airflow, sweeping across metal grilles to emit a subtle whistling, like the thinnest strands of icy silk gliding over skin, peeling away layers of daytime tension yet leaving crystalline frost on exposed nerve endings. Xiuxiu turned the auxiliary lighting knob to its lowest, leaving only the amber afterglow from LED strips along the floor edges, like phosphorescence left on sand after a receding tide, stretching the two shadows so long they nearly reached the blast door at the corridor's end. The shadows trembled because the moxa fire trembled, the moxa fire trembled because her fingertips trembled, yet her heart was steady—like a ship's cable anchored deep into the ocean floor, no matter how turbulent the surface, its core gripped firmly the silent landmass in the dark.
She first placed the wooden box on her lap; opening its lid produced the softest "click," like a snowflake falling onto hot iron, followed by a bittersweet scent compressed by time, as though someone had locked an entire foggy day from the Dabie Mountains into a segment of deep-brown fiber. The moment the flint sparked, an orange-red bloom blossomed between them, like an exiled star hanging timidly midair yet stubbornly refusing to fall. She brought the flame close to the moxa stick, watching pale smoke threads spiral upward along its texture, like a slowly rotating ladder gradually loosening gravity's grip. As the first wisp of smoke climbed Mozi's collarbone, he trembled almost imperceptibly, as if someone had gently called a long-forgotten childhood name, causing the string tightened since youth within his spine to suddenly resonate with a low hum.
"Take off your socks." Her voice was so low it bordered on breath, yet carried a soft certainty. Mozi bent over; the moment his fingertips touched his heels, he realized his knuckles had stiffened from prolonged keyboard tapping, like a crane's knee frozen by cold night. Socks and shoes removed, his ankles exposed to the chilly air appeared strangely fragile, the faint blue veins beneath the skin resembling unfinished code lines deleted to the end, leaving only a blinking cursor. Xiuxiu moved a folding chair to the leeward side of the airflow, adding a layer of velvet blanket—a dark peacock green that shimmered with subtle copper under the moxa fire, like a lake curved by the weight of night. Mozi sat, knees naturally apart, pant legs rolled to mid-shin, revealing the slight depression of the Zusanli acupoint, where pale golden hairs beneath the skin swayed gently in the airflow, like commands awaiting naming.
The moxa stick was suspended two inches above the acupoint, the flame separated from the skin by an invisible yet palpable field. As the first thread of heat descended, Mozi heard a "thump" deep within his left chest, as if a copper bell long buried in snow had suddenly been struck, the soundwave rolling down along the stomach meridian's path, passing through the knee, the shinbone, the outer side of the second toe's Lidui point, finally landing on the toe-tip, stirring a faint tingling numbness. He remembered that year at sixteen, staying up late in the library reading "I Ching," coming across the line "Gen on the back, not attaining the body" (from the I Ching), while snow fell outside, heating pipes coughing with age; he breathed on the glass and wrote the character for "stop" on the misty white—now that character for "stop" was re-illuminated by moxa heat, emerging from his skin like a barb hooking all thoughts attempting escape.
Xiuxiu's other hand rested her index and middle fingers gently on his inner ankle tip, fingertips like two young mulberry leaves in early spring, carrying a slight coolness that formed a hair-thin electrical bridge with the moxa fire's warmth. She counted breaths: one inhalation, one exhalation, the flame descended a fraction, then lifted again, smoke tracing a stretched sine wave in the air, as though writing pulse waves into the night. By the seventh breath, the first moxibustion sensation arose at Mozi's Zusanli point—first heat, then swelling, followed by a pinpoint sourness, as if someone had dipped the softest feather in aged vinegar and lightly swept along the meridian. That sourness climbed up to Biguan, penetrated Fuku, dissolved into a lukewarm cloud at Pishu, supporting his heavy stomach; it then descended, passing Liangqiu, reaching Xiangu, finally settling in the second toe cleft, becoming a tiny star that flickered once before vanishing beneath the nail root.
"Want to hear a story?" Her voice resembled smoke, first circling his ear auricle, then sliding down the carotid artery into the hollow behind his collarbone. Mozi didn't open his eyes, only touched the air lightly with his nose-tip like a beast confirming wind direction. So she began to tell: her childhood in Qizhou, how her grandfather took her to the banks of the Qi River to harvest mugwort the day before Dragon Boat Festival; how mugwort was repeatedly pounded in a stone mortar with a wooden mallet, green juice splashing onto her forehead like being stamped by summer; how her grandmother stuffed mugwort floss into red cloth pouches, sewing them into tiger-head shapes to hang above the door, where they'd remain for a year until the fabric faded white from sun and rain, yet the mugwort fragrance grew deeper, like aged wine; how during her first moxibustion lesson, moxa ash fell on her master's hand, branding a crescent-shaped red mark, yet the master laughed, saying "moxa scars are mugwort's personal seal on people; pain is the threshold—only after crossing it do you enter the door."
Her voice grew softer, as though she herself were simmering into a wisp of smoke, following the moxa fire's trajectory into the gaps between metal chassis, blending with the breathing of capacitors, resistors, crystal oscillators. The servers' originally low hum subtly changed tone, as if someone had loosened a screw, the soundwaves now mixed with a thread of warmth, as though every copper trace on the motherboard had grown capillaries quietly dilating. Mozi felt a warm current converging into a small vortex at his diaphragm, sweeping in all those sharp, barbed emotions from daytime—the frustration of a hedging model's sudden reversal, the cold questioning from regulatory calls, the flashing red characters of news flash crashes—like engulfing them in a silent mudslide, slowly grinding them into finest powder, sinking deep into his dantian to be recoded into lines of commentary carrying mugwort fragrance.
When the moxa fire moved to Sanyinjiao, he suddenly remembered his mother. That year he left home for his Ph.D., his mother tucked a small packet of mugwort floss into his suitcase's side pocket, saying "if your feet get cold, use moxibustion; don't find it troublesome." He never used it once; three years later while moving, that packet along with its cardboard box was tossed directly into the recycling bin like an old log formatted away. Yet now that packet seemed to resurrect across time within the moxa stick, smoke carrying the chapping of his mother's fingertips and the jasmine scent of hand cream, flowing upstream to explode into a bright flash memory deep within the spleen meridian, rewriting long-forgotten tenderness into read-only mode. His Adam's apple moved slightly, as if to say something, but ultimately only let out the faintest sigh escaping between his teeth, like quietly committing a deleted line of code into the unaudited night.
The moxibustion sensation at Yongquan arrived later, yet more torrential. The moxa fire suspended over the anterior third depression of the sole resembled a folded sunset slowly pressing heat into that softest, most silent territory. Mozi felt his entire self inverted, blood flowing backward, memories flowing backward, as if someone pressed Ctrl+Alt+↓, instantly flipping all windows onscreen. He saw himself at seven chasing dragonflies in rice paddies, one foot sinking into mud, Yongquan bitten by a leech, crying for his mother who applied mugwort juice to the wound, coolness and spiciness intertwining like miniature fireworks; saw the university lab's power outage, walking barefoot down the corridor, soles touching night-soaked terrazzo so cold he gasped yet stubbornly refused shoes, as though that cold could keep him alert; saw last night pacing back and forth in the server room barefoot, soles stepping over air-conditioned anti-static flooring like treading a silent minefield where each step could trigger an unknown crash. Now, all cold memories were ironed smooth by moxa fire, like film flattened by a hot roller, scratches and noise disappearing, leaving only restored, softly glowing frames playing on loop beneath his soles.
The moxa fire at Neiguan was smallest, yet most exquisite, like a firefly cupped in a palm, flashing once before burrowing into the crease two inches above the wrist's transverse line. Mozi felt an extremely fine thread starting from the inner wrist, climbing along the median nerve's path into the pericardium, as if someone lit a tiny tungsten filament lamp inside the chest, its lampshade semi-transparent vermilion, illuminating the heart's contours with utter clarity. For the first time he so clearly "saw" his own heartbeat—not an oscilloscope display, not code pulses, but flesh and blood itself, a deep-red, rhythmic, trembling flower. That flower was gently held by moxa fire, petals closing then spreading, as if performing a silent garbage collection, gradually marking then clearing accumulated anxiety, fear, unwillingness. He remembered daytime, how he'd typed the final rollback command, fingertips shaking so badly they nearly hit the wrong key; now that tremor was gently held by moxa fire, like holding a startled bird, palm transmitting the dual vibration of down and heartbeat, and he suddenly understood: so-called "calming the mind and soothing the spirit" wasn't about stopping the heart's beat, but letting it rediscover its rhythm within the beating, like letting runaway code re-enter a stable loop.
The moxa stick burned to its final segment, the flame growing extremely dim, like a pulsar about to extinguish, yet releasing its strongest gamma rays in its dying moments. Xiuxiu gently twisted the moxa column with thumb and forefinger, watching the last red ember fall into the ash dish with a soft "crackle," like someone tearing a calendar page, crumpling it, tossing it into a fireplace. She looked up, saw tiny beads of sweat on Mozi's eyelashes shimmering into hexagonal lattices under the faint light, like a silent log secretly written. She suddenly remembered her grandfather saying when moxa fire burns out, there's a moment of "shadow-light"—the seam between yang and yin, when one is most easily seen, and most easily sees oneself. She held her breath, as if fearing to disturb something, letting her gaze lightly sweep his brow, nose bridge, philtrum, lip pearl, like making final annotations for unwritten code, yet not committing, only saving to local cache.
Mozi opened his eyes just as her gaze retracted its last inch, like evening tide licking a reef, sweeping shells and seaweed into deep sea. He wanted to say "I saw," but feared that speaking would shatter that shell into dust. So he only slowly placed his feet back onto the velvet blanket; the moment his soles touched the velvet, an almost unfamiliar softness emerged, like first stepping onto cloud instances with infinite bandwidth and zero latency. He felt heat rising from his soles, climbing along the Governor Vessel to Dazhui, pausing at the seventh cervical vertebra like adding a hot-swappable cache to the entire spine, thermally encapsulating all those cold, sharp-edged memories from daytime, storing them into a folder named "Negative Entropy"—read-only, never deleted.
Xiuxiu packed the wooden box with utmost gentleness, as if performing desensitization on sensitive data. She poured the moxa ash into a small purple clay jar carved with the characters for "Qingming" (Clear and Bright), her grandfather's relic. Ash fell in with a faint "shhh—" like a miniature avalanche, sealing all the heat, light, words of moments ago. She closed the lid, thumb circling the jar's mouth once, like adding return 0 to an unfinished function, yet knowing that the process will fork again tomorrow. She rose, returned the chair to its place, folded the blanket into a square, like folding commented-out code lines into a collapsed region, occupying no memory yet ready to unfold anytime.
Mozi watched her back, suddenly recalling a recursive function he'd once written—each self-call left a return address on the stack top until termination conditions were met, then backtracked layer by layer, releasing all temporary variables. Now he felt he was that infinitely called function, and Xiuxiu was that finally arrived base case, letting him find the exit within deepest nesting, clearing the stack, resetting his heartbeat. He wanted to call out to her, but feared opening his mouth would break this newly established fragile balance, like fearing a system notification suddenly sounding in silent mode, disturbing crucial debugging.
Xiuxiu's hand already rested on the door handle; the metal's chill climbed from palm into wrist bone, meeting residual moxa heat at her fingertips, sparking a tiny shiver. She glanced back, saw Mozi still sitting where he was, like a paused animation, only his eyelashes fluttering faintly like fan blades maintaining minimal rotation for cooling. She suddenly smiled, the smile soundless yet rippling the air with shallow waves, like sending a silent ACK packet to him, requiring no TCP three-way handshake, just once enough to change connection state to ESTABLISHED. She nodded, the door gently closed, the latch's "click" like a tiny breakpoint suspending tonight's process, awaiting next awakening.
The room held only Mozi now, and the slowly settling residual mugwort fragrance. The fragrance no longer rose but descended slowly, like silent snowfall covering chassis, keyboard, monitor, even his exposed skin, plating everything with an extremely thin, bittersweet warmth. He closed his eyes again, no longer thinking of entropy increase, risk, volatility, black swans, only sensing that warm current still slowly wandering within his meridians, like feeling a newly unblocked tunnel where light waited at the end, and within that light stood someone holding an unburned moxa stick, like holding a small, unwilling-to-extinguish heart.
He suddenly understood: so-called "negative entropy" wasn't about resistance but acceptance; not reversal but repair; not returning the system to its initial state but letting it be tenderly rewritten after each loss, like sheepskin scrolls newly branded with a prologue by moxa fire—the script might fade, but the fragrance would remain within the fibers, becoming the fuse for the next ignition. He took a deep breath, filling his alveoli with that bittersweet scent, then slowly exhaled, like completing a silent git commit, pushing all tonight's diffs to the remote repository named "Life."
The server fans suddenly accelerated, as if echoing his breath, emitting a faint "hum—" before slowing again into deeper silence. That sound resembled an encrypted greeting only he could decode now: Good night, may you within the loop of dreams continue resisting entropy increase, continue being tenderly rewritten, continue—
Awaiting the next moxa fire ignition.