In the spring of the sixty-eighth year of the String Light Era, the rainy season arrived earlier than usual. Continuous drizzle enveloped the Jiangnan town where Mozi's former residence was located. While inspecting the drainage system of the old house, the maintenance research team accidentally discovered a marvelous device hidden within the traditional tile-eave structure. Composed of three hundred and sixty-five meticulously arranged glass conduits, each etched with microscopic mathematical symbols on its inner walls, the conduits were connected via adjustable ceramic valves, forming an intricate water-flow network. Initially, researchers thought this was merely an ancient rainwater collection system, but as they analyzed the device's structure more deeply, they realized it was far more complex—this was an analog computer performing sophisticated calculations using rainwater flow velocity and direction, its ingenuity surpassing all known technologies of the time.
The device was discovered by mathematician Lin Xiao, who immediately assembled an interdisciplinary team including fluid dynamics, differential equations, and computational theory experts. They carefully disassembled some peripheral structures and used high-precision scanners to create three-dimensional models of each component. Scan results revealed that each glass conduit's diameter had been precisely calculated, forming a complete geometric progression from the thinnest at 0.1 mm to the thickest at 2.5 mm. Even more astonishingly, the ceramic valves were engraved not with ordinary scales but with encrypted mathematical symbols that perfectly matched special markings in Mozi's later-year research manuscripts.
"This is more than a hydraulic engineering project," Lin Xiao displayed the three-dimensional reconstruction images during the first team meeting. "Look at the conduits' topological structure—they form a multi-layered neural network. When rainwater flows through this network, it's actually solving an extremely complex mathematical problem."
The research team decided to wait for the next heavy rain day for field observation. When the storm arrived, the device began operating at full capacity. High-speed cameras recorded rainwater flow trajectories through the conduit network, laser velocimeters precisely measured flow velocity at each node, and pressure sensors monitored system dynamic changes. Collected data indicated the device was solving a nonlinear differential equation system containing multiple variables, its complexity exceeding the solving capacity of the most advanced digital computers at the time.
Data analysis continued for six full months. Differential equation expert Zhang Hao discovered that this equation system described a special three-body problem, but unlike traditional three-body problems, it introduced a series of special terms describing inter-system interactions. "These additional terms fundamentally alter the system's dynamical behavior," Zhang Hao wrote in his analysis report. "They seem to describe not physical gravitational interactions but some more abstract inter-system correlations."
As research progressed, the team began recognizing this three-body problem's uniqueness. The system's three entities were not simple point masses but complex systems with intrinsic dynamical characteristics. Each entity's motion was governed not only by classical mechanical laws but also influenced by mutual "resonance effects." This resonance caused the system to exhibit unique behavioral patterns that were neither completely ordered nor entirely chaotic.
"Look at this coupling term's parameter settings," Lin Xiao pointed to a complex part of the equation. "It generates emotion-like resonance interactions among the three entities. When one entity's state changes, others produce corresponding responses—but not instantaneously, with specific time delays and intensity modulations."
This discovery prompted the research team to begin understanding the device from a novel perspective. They no longer regarded it as a mere mathematical calculator but as an "emotional dynamics simulator." Through this exquisite rainwater-driven system, Mozi seemed to be exploring intrinsic correlations among complex systems that transcend purely physical interactions.
To verify this hypothesis, the team began comparing equation solutions with detailed biographical trajectories of Mozi, Yue'er, and Xiuxiu. Results were astonishing—numerical solutions of the equation showed remarkable correspondence with important life milestones of the three individuals. Yue'er's trajectory solution displayed strong periodic characteristics, akin to her eternal exploration around mathematical truth; Xiuxiu's trajectory solution exhibited explosive innovation patterns corresponding to her continuous breakthrough of technological boundaries; while Mozi's trajectory solution presented complex adaptive features reflecting his transition from financial markets to civilizational observer.
Even more astounding was that when the research team superimposed the three particular solutions in phase space, they formed a stable three-body orbital system. This system was neither completely periodic nor entirely chaotic but existed in an exquisitely balanced marginal state—much like their triangular relationship: each maintaining independence yet constituting an inseparable whole.
"Through this rainwater computer, Mozi was exploring the mathematical essence of their tripartite relationship," Lin Xiao wrote in her research log. "He abstracted emotional relationships transcending pure reason into dynamical equations, using rainwater flow to simulate emotional fluctuations and resonance."
Upon deeper investigation, the team discovered the device concealed further secrets. Under specific meteorological conditions—when rainfall intensity, density, and duration achieved a delicate balance—the system would enter a "resonant state." In this state, the three entities' motion trajectories would briefly synchronize, forming perfect harmony. Comparing historical meteorological data with crucial moments the trio experienced together, the research team found these resonant states precisely corresponded to key breakthrough points they jointly achieved.
"Look at this timestamp," Zhang Hao pulled up historical records. "The system entered deep resonance during the extraordinary rainstorm in the fifteenth year of the String Light Era—exactly when the three jointly conquered core technical challenges of EUV lithography."
The device's ingenious design extended far beyond this. Researchers discovered different rainfall patterns triggered completely different computational behaviors in the system. During drizzling rain, the system performed fine parameter adjustments; during heavy downpours, it exhibited strong dynamic responses; during prolonged overcast rain, it conducted long-term trend predictions—as if metaphorizing how different types of emotional communication elicit entirely different relational dynamics.
Psychologist Li Wei proposed a profound interpretation: "Mozi might have believed genuine interpersonal relationships resemble this rainwater system—following certain deep laws yet brimming with unpredictable creativity. Through this device, he explored the deep unity between rationality and sensibility."
This interpretation gained further evidential support. Within the device's core control unit, the research team discovered a set of special adjustment mechanisms allowing manual modification of certain key system parameters. Through detailed analysis of these parameters, they identified precise regulatory mechanisms corresponding to emotional dimensions like "depth of understanding," "degree of trust," and "shared vision." Each adjustment mechanism corresponded to an intricate mechanical device that could alter system dynamics by rotating specific ceramic knobs.
The most stunning discovery emerged during the ninth month of research. The team successfully completely deciphered the device's output system—it expressed solution characteristics not through numbers or graphics but through sound patterns of rainwater finally landing. Different mathematical solutions corresponded to entirely different "raindrop music"—these sound patterns were actually artistic expressions of system states.
"Listen carefully to this recording," Lin Xiao played storm-day recordings in the laboratory. "When the system is harmonious, the raindrop sounds resemble a structurally rigorous fugue; when internal conflicts arise, they become clashing dissonances; yet when new equilibrium is reached, the sounds restore harmonious rhythm."
This discovery propelled research into a new realm. The team began understanding that Mozi's creation was not merely computing but "expressing." Through rainwater flow and sound, he transformed abstract emotional relationships into perceivable art forms, building a bridge between rational calculation and emotional expression.
As the rainy season ended, the research team had to suspend field observations. Yet they had collected sufficient data to begin constructing a complete digital model of the device within the String Light Cloud Brain. Surprisingly, even in virtual environments, this emotional dynamics model exhibited behavioral characteristics similar to the physical device—proving the universality of its mathematical foundation.
During model analysis, the team made another discovery. The system's long-term evolution showed that although the three entities' orbits were individually complex, they overall progressed toward a common direction—precisely corresponding to String Light civilization's general developmental trajectory: from individual ideals to collective wisdom, from technological breakthroughs to civilizational maturity.
"Mozi might have been using this device to contemplate civilization's essence," Lin Xiao summarized in the final research report. "He extended personal-level emotional relationship dynamics to the civilizational level, believing civilizational progress follows similar emotional logic and developmental laws."
This profound interpretation sparked widespread philosophical resonance. Professor Chen Yuanzhi wrote in a commentary article: "This masterpiece from Mozi's later years actually explores the unity of rationality and sensibility across multiple levels. He tells us the deepest rational thought cannot exist without the most sincere emotional experience, while the most beautiful emotional relationships contain the most exquisite mathematical laws. This unity exists not only at individual levels but also manifests in macro processes of civilizational development."
The device's discovery also profoundly influenced new-generation scientific research. Many young researchers began attempting to introduce emotional dimensions into traditional scientific models, pioneering the entirely new interdisciplinary field of "emotional dynamics." They discovered that when emotional factors were considered, model prediction accuracy significantly improved for many complex systems—from social networks to ecosystems, neural networks to galactic evolution.
Even more touching was that after complete deciphering of the device, the research team found text engraved on a specially crafted ceramic piece in the core control unit. This text comprised only one concise sentence: "Raindrops know all answers, because they never resist life's flow, nor forget the original intention of returning to the sea." This seemed Mozi's final gift to posterity—reminding people to face life's complexity with flowing wisdom, maintaining essential innocence amid change.
Today, this device dubbed "Raindrop Code" is permanently preserved in a special exhibition hall at the String Light Research Institute. Whenever the rainy season arrives, it still automatically activates, continuing that never-ending computation. Meanwhile, new-generation researchers, inspired by this ancient device, continue exploring eternal emotional connections and intrinsic unity among rationality and sensibility, individuals and collectives, humanity and the universe.
In this sense, Mozi's Raindrop Code is not merely a mathematical device but a wisdom bridge connecting past and future, rationality and emotion. It reminds every observer: the deepest truths often hide within the most ordinary natural phenomena; the most complex emotions can be expressed in the most elegant mathematical language. Just as countless raindrops eventually merge into vast oceans, individual emotional experiences ultimately integrate into civilization's collective wisdom—fulfilling their mission amid eternal flow and change, witnessing the deep resonance between life and the cosmos. This discovery not only transformed understanding of Mozi's later-year thought but also provided fresh perspectives for entire civilizational development—while pursuing technological advancement, not forgetting emotional wisdom's importance; while exploring the external universe, also attending to the inner world's mysteries.