Economic cycles, as the underlying pulse of market economies, have consistently permeated human economic activity throughout history. Their essence lies in the non-equilibrium dynamics of production, consumption, and investment over time, leading to alternating phases of expansion and contraction. This phenomenon is typically deconstructed into four stages: the economic overheating of the boom period, akin to the blazing summer sun; the demand contraction of the recession period, like autumn winds sweeping away leaves; the market freeze of the depression period, reminiscent of winter hibernation; and the signs of recovery in the revival period, similar to the sprouting of spring.

Based on the varying lengths of these fluctuations, academia categorizes economic cycles into long, medium, and short cycles, corresponding to Kondratiev waves, Juglar cycles, and Kitchin cycles, respectively. These cycles function like interlocking gears, collectively driving the complex operations of the economic system.

The trajectory of long cycles is deeply imprinted with the genetic code of technological revolutions. Kondratiev, through his analysis of 200 years of industrial revolution history, identified major innovative waves such as the steam engine, railways, electricity, and information technology. Each of these waves, occurring roughly every 50-60 years, triggered a profound restructuring of the economic landscape. This "creative destruction" mechanism was particularly evident in the fifth Kondratiev wave, where the internet revolution of the 1990s significantly boosted employment in the U.S. information technology sector. The current rise of artificial intelligence and quantum computing heralds the dawn of the sixth Kondratiev cycle.

The medium-term Juglar cycles resonate closely with equipment investment. Juglar's empirical research on capital flows revealed a 7-10 year cycle of equipment renewal. When businesses collectively replace old machinery with automated production lines, it often stimulates credit expansion and employment peaks. Conversely, this can lead to capacity clearance and market contraction. China's capital market experienced two historic bull runs approximately 9.5 years apart, validating the Juglar cycle's relevance in Eastern markets.

Short-term Kitchin cycles focus on inventory fluctuations. Kitchin's analysis of business data from 1890 to 1922 identified a 3-4 year inventory adjustment cycle. When businesses misjudge demand and stockpile raw materials, the resulting oversupply leads to price reductions and inventory clearance, forming a "production surplus-inventory liquidation" loop. This phenomenon was starkly illustrated during the global pandemic, as the hoarding and subsequent disposal of pandemic-related supplies exemplified the Kitchin cycle's micro-mechanisms.

Different cycle theories reflect diverse perspectives on understanding economic laws. Schumpeter viewed technological innovation as the root of cycles, while Hicks focused on credit cycles. Kuznets introduced the 20-year building cycle, and the century-long debate between Keynesian and Hayekian schools of thought highlights the philosophical divide in cycle response strategies.

Currently, the global economy is experiencing a complex interplay of multiple overlapping cycles. The fifth Kondratiev downswing coincides with a Juglar trough in equipment investment and volatile Kitchin inventory cycles, creating a resonance effect of "long-term decline, medium-term fluctuation, and short-term spasms." This intertwined state is particularly evident in the energy sector: technological breakthroughs in photovoltaics have significantly reduced electricity costs, but short-term oversupply of silicon materials has led to price crashes. Traditional automakers face substantial investment demands for electrification but also grapple with long-term technological uncertainties. Understanding this multi-cycle interplay is crucial for policymakers and market participants. Japan's "lost decades" serve as a cautionary tale of misjudging the Kondratiev downswing and continuing investments in traditional industries. In contrast, Tesla's navigation through multiple cycles, balancing long, medium, and short-term dynamics, has culminated in a trillion-dollar market valuation milestone. Historical experience shows that economic cycles are both objective laws and cognitive frameworks, neither mechanically deterministic nor randomly chaotic, but a complex interplay of technology, institutions, and human nature across time and space. Only by establishing a multi-cycle embedded thinking model can one strategically navigate the eternal ebb and flow of economic prosperity and decline.