Thinking about eternity is not simply an esoteric mental exercise. It’s a cure for boredom, a panacea for the trivial, a respite from the mundane. And it’s the sort of thinking best done on your own. If you say to your spouse, “Let’s stay in tonight and bat around the notion of eternity,” chances are that he or she will look at you blankly and reply, “I was hoping it would never come to this.”

Approach it calmly – there’s no need to work yourself up into a lather by drinking turpentine and spitting fire. But be careful. Intellectual escapades like this are deceptively difficult and it’s easy to blow a synapse, or worse.

Witness the man of stone. It takes an eternity for his eyes to blink even once. He stares at the sun, the moon, and the stars as they pass by turns overhead. One day he crumbles and only a pile of rubble remains. He wasn’t cut out for the eternal.

To avoid such a fate, you should first distinguish between eternity and time. Note, however, that it’s easy to bogged down in the vagaries of time, which are considerable.

In the fifth century, Augustine of Hippo famously confessed, What then, is time? If no one asks me, I know what it is. If I wish to explain it to him who asks me, I do not know.

Best ask someone else then.

Like a geologist, who will show you that time is stratified into layers like the pages of a book. Or a paleontologist. He or she will hand you a fossil trilobite and describe it as an icon of time past. Astronomers will point to different stars that are billions of years old. Meanwhile, children will tell you their ages to the nearest half year and poets will lament its passing.

Time’s passing is a great enigma for science and you may be interested to know that some physicists will tell you that both past and future are fixed and time is laid out in its entirety in a timescape, akin to a landscape. There, all past and future events are laid out together. No special moment is singled out as the present because there’s no known mechanism to convert future events into present then past events. This is why the universe often fails to wish you a happy birthday.

Here is where a little Plato comes in handy. He described time as an imperfect moving image of eternity which remains forever at one. We don’t know what he means either. Perhaps each moment of your life is a frame of a film strip illuminated by the brilliance of the eternity’s lamp? Try that on your mental trapeze.

Whether time passes or is simply an illusion, an appreciation of its fleeting nature could help in pondering eternity. You can start by thinking about things that are ephemeral. Some examples will help.

Shooting stars are ephemeral, as are summer thunderstorms, rainbows and haloes around the sun. Unfortunately, the full moon is ephemeral too, even though its glistening light seems to hold everything still as a stone. You can’t step in the same river twice, so the river is definitely ephemeral. Blossoms and leaves also come and go.

But don’t get carried away. Some things that appear ephemeral are actually eternal. Listen to Basho:

Old pond:
frog jumps in,
sound of water.

The frog jumped in three centuries ago and today the sound waves of that tiny splash continue to ripple. But look, there is the frog again on the lily pad, waiting to jump. Now it’s on a log. In it goes, head first, legs last, another splash. Now it’s back on a lily pad, spying a bug on the surface of the old pond. Once more it lunges in to the sound of water.

Once you see the frog, you know that it exists in a timeless space, in the old pond of your mind, always waiting, always ready to jump, always jumping and splashing into a vast silence that erupts briefly before resettling into soundlessness. When you can imagine moments like this standing still forever, and repeating forever, you are starting to get the hang of eternity.

Remember the Little Prince, his sheep and his flower? They are eternal.

On the other hand, according to Magritte, eternity is a cylindrical block of butter with a spatula in it, on a pedestal for all to see, between the bronze heads of the suffering Christ and the scowling Dante. If you stare long enough at the painting, the butter will begin to melt before your eyes.

Or look at Giacometti’s walking figures. Corroded as if baked too long in time’s oven, do they stride from the present into the future, gazing blankly ahead, or from one eternity to another?

Or read some Emily Dickinson. She often sailed to eternity and back in a single line of verse.

Why not take a trip to Paris and admire all the pairs of lovers lolling on the bridges or spoon feeding each other crème glacée in the cafés? Rather than smashing their heads together in a fit of jealousy, pose yourself a philosophical question: What are they doing? Aren’t they trying to suspend time and glimpse eternity? Extend your stay and see if you can become one of them. The crème glacée will do you good.

Alternatively, if you want to think about eternity as a duration, you could think about the spacecraft, Voyager 1, launched in 1977 and now leaving the solar system at a speed of sixty thousand kilometers per hour. Forty thousand years from now it will drift past another star, AC +79 3888, seventy-fifth on the list of nearest stars to Earth, though it won’t come within shouting distance of any of that star’s putative planets. In two hundred and ninety six thousand years, its sister ship, Voyager 2, will drift past Sirius, the brightest star in the sky. Go ahead. Think about the sparseness of space, think about two hundred and ninety six thousand years and you’ll get a hint at why Pascal shuddered “The eternal silence of these infinite spaces frightens me.”

Treat it all more circumspectly, then, and mull over this quote by Thomas Browne, “The night of time far surpasseth the day, and who knows when was the equinox?”

Despite that teaser, it may be hard to improve upon the wisdom of the shepherd boy in the tale by the Brothers Grimm. In response to the king’s question, “How many seconds of time are there in eternity?” the boy describes a mountain in Lower Pomerania two and a half miles tall and just as wide and deep, and he says, “Every hundred years a little bird comes and sharpens its beak on it, and when the whole mountain is worn away by this, then the first second of eternity will be over.” Continue in this vein and try to convince yourself that the number of years between here and eternity exceeds the number of grains of sand in all the beaches and deserts of the world, the number of stars in all the galaxies and even the number of particles in the known universe.

But you should be aware that some people, like Dostoyevsky, weren’t impressed with such efforts to create an abyss out of time. We always imagine eternity as something beyond conception, he said, something vast, vast! But why must it be vast? Instead of all that, what if it’s one little room, like a bathhouse in the country, black and grimy and spiders in every corner, and all that? Book one for the summer and see if he was right.

Even the Buddha wasn’t sure that it was possible for such thoughts to get anywhere. “Our theories of the eternal,” he’s reputed to have said, “are as valuable as those of a chick that has not broken its way through its shell might form of the outside world.”

Don’t let that deter you. According to cosmologists, the universe had a beginning, so it is not eternal. One day, long after the man of stone has crumbled, the stars will blink out, and, thanks to dark energy, the mysterious force that’s driving the universe apart, eventually all the other galaxies will be pushed away too far for us to see them. After the bird saws off a couple of seconds of eternity, there won’t be much left in the cosmos except for black holes.

This kind of thinking might depress you, but take heart. In the 1980’s, physicists tried to find out if the proton, the elementary particle that makes up all normal matter, including you, me and crème glacée, might one day decay. Having found no evidence, physicists now think protons are eternal. So, after your mental trapeze artist has dismounted and you have exhausted your experiment with eternity, and your experiment with life, your protons will go on living.