Carolus Linnaeus, an 18th-century Swedish botanist, became so enamored with the rhythmicity that lives within the rhythms of plants, he deigned, planned and grew a garden by which he could tell the time. He planted flowers that opened or closed their blossoms at specific intervals, precisely marking the hour, from morning to evening, throughout the day.
All life vibrates to these inner rhythms. These daily rhythms guide most living things, and they often approximate a 24-hour cycle - even when isolated in a laboratory. These circadian rhythms (from circa, "about," and dies, "daily") live deep inside us all. They are nearly impervious to alteration, and refuse to be extinguished. In normal daylight, mice in laboratories begin running on an exercise wheel about dusk, run intermittently through the night, and sleep during the day. Even when their cages are kept artificially dark for long periods, the mice maintain this circadian rhythm for several weeks.
Sometimes, I have walked the beach at night, and witnessed a peculiar luminescence in the waves, a microscopic algae that illuminates the darkness. It is nonluminescent during daylight hours - even under artificially darkened laboratory conditions. Circadian rhythms will entrain, or adjust, to an artificial light-dark cycle - but only if it does not deviate drastically from a 24-hour cycle. A test animal exposed to 11 hours of light and 11 hours of dark will gradually entrain to a 22-hour cycle; if exposed to 13 hours each of light and dark it will entrain to a 26-hour cycle. But as soon as the artificial cycle is removed, the natural cycle returns. If the cycle is varied too much - if we try to entrain an organism to a thirty, thirty-five or forty-hour cycle - the creature will soon give up trying to adjust, and return again to its original 24-hour rhythm.
Photoperiodism describes an organism's ability to respond to varying periods of light and dark. Deciduous trees drop their leaves under the influence of the shorter days of autumn, and grow leaves again during the lengthening days of spring. Florists often use this photoperiodism to "trick" greenhouse plants into producing blossoms out of season by exposing them to unseasonable periods of artificial light.
Most organisms have more than one circadian rhythm. In human beings, different circadian rhythms govern our wake-sleep cycle, glandular secretions, highs and lows in our body temperature, even the retention and excretion of urine. No matter how the light around us is manipulated or corrupted; even if researchers alter the hours we sleep, change our patterns of eating, or manipulate our nutrition or our diet, no matter the most strictly controlled laboratory conditions, no organism can ever be entrained completely away from its true inner rhythm. In the end, we will always return to the way we move, entrained within our rightful place, in the midst of all the natural world. We inexorably belong to an enormous, living, breathing, magnificently bio-spiritual rhythm of Life and Time.
Not only do we use this inner pulse to guide our survival, we also use it to find our way in the world. Most animals navigate their journeys using natural rhythms and seasonal information - tides, blooming vegetation, climatic conditions, subtle changes in sound and light - to orient themselves. Using circadian rhythms, and factoring the angle of the sun above the horizon, then combining those with the shifting relationships of dark and light in each day, they craft an inner compass that grants them astonishingly accurate access to their exact geographical position on the earth.
Oysters open their shells when the moon is high. The chambered nautilus forms a new chamber in its spiraled shell every lunar month. Bees respond to the polarization of sunlight and orient themselves by the pattern it forms in a blue sky - even when the sun is behind the clouds.
There is a hum the earth makes. When seasonal winds pass over the waves upon the sea, across the mountains around the world, the earth and sea and mountain make a sound, a quiet, persistent music is born. This low-frequency pulsation is audible to migrating birds thousands of miles away.
By listening to the music of the earth, birds find their way home. Many birds also have an inner ability to orient themselves to true north; when they fly at night, they use patterns and movements of stars to guide their flight. Even in a planetarium, when the night sky is projected on the ceiling -birds will fly precisely in rhythm with the seasonal dance of the stars.
Jesus said, Whomever has ears, let them hear. We are blessed with ears that allow us to hear music, and birds awakening at sunrise, and, if we take the time, if we listen with tremendous care, wonder and awe, to the symphony of the spheres, we, too, will hear those potent inner rhythms within us all speak to us, and tell us where we are, and where we may need to go.
No matter, then, our fifty- and sixty-hour work weeks, this refusing to stop for lunch, the bypassing sleep and working deep into the darkness. If we stop, if we return, if we rest, our natural rhythms reasserts themselves. Our fundamental wisdom, our self-correcting balance, they are with us always. They come to our aid, and can find, again, our way to all that is good, necessary and true in our days, in our journey.
There is within us something that Thomas Merton called a hidden wholeness. We can get frightened, we can work too hard and long, we can feel confused, and begin to lose our way. But we cannot ever be permanently seduced, entrained or bullied out of our natural rhythm. It cannot be taken from us.
However, we can be seduced by promises of achievement, productivity, success, glory or just mindless acquisition. And in that frantic, desperate rush and pressure of the complexities of daily life, to barely make it from paycheck to paycheck - we can refuse to listen.
Now, more than ever, we are called to tend to the well-being of one another. We must be our sister and brother's keeper. At the end of the day, we are invited to gather, in the company of like-hearted people, to be good, honest mirrors, to remind one another of our reliable hidden wholeness, and to remember who we are, what we know, and how the rhythms that saturate the whole of the natural world live and thrive in each and all of us - if we will only listen.