THE SIGNATURE OF ALL THINGS, by Elizabeth Gilbert

From the very first page of Elizabeth Gilbert’s mammoth new novel, we know we are no longer in the realm of “Eat, Pray, Love” — no longer vaulting from woe to wisdom via food, sex and an exotic itinerary. The book’s epigraph alone indicates we are on different ground: “What life is, we know not. What life does, we know well.” Which is to say that Gilbert’s novel will deal with the wonderfully baggy preoccupations of the Victorian age: faith, doubt and the biggest, most baffling puzzle of all: What is life? Why are we here? And why is it that the more we decode nature, the less we know how nature began?

These are the questions that consume our heroine, who struggles between the rigors of scientific inquiry and gossamer notions of love. Alma Whittaker, born in January of 1800, is a clever girl — curious, big-boned, sturdy — and fascinated by her father’s thriving business of botanical imports. But she is also alert to the world and the limitations that she as a woman will face in it. Becoming a botanist in her own right, she is plunged deeper and deeper into the mysteries of life itself. “The Signature of All Things” is that rare literary achievement: a big, panoramic novel about life and love that captures the idiom and tenor of its age.

The story begins in England in the 1760s, just as Europe swings into vigorous botanical exploration. Henry Whittaker, Alma’s father, is born poor near the horticultural splendor of Kew Gardens. Caught pilfering trees from Kew, young Henry begs to be spared the noose. Arguing that he knows something about plants and might be useful, he talks his way onto one of Captain Cook’s expeditions, then canvassing South America for the medicinal plants that will form the basis of a vast pharmacological industry. Whittaker is soon happily pilfering bark of the cinchona tree — a medicine that cures malaria — from the Peruvian jungle, but when he goes back to England with high-flown dreams of joining the Royal Society of Fellows, he is laughed at, ridiculed. Offended, he sells his botanical treasures to the Dutch East India Company instead, immigrates to the United States, becomes a very rich man and lands himself squarely in Philadelphia society.

So it is that his daughter Alma is born a rich American, far from the poverty of his childhood. Growing up in a Palladian mansion at White Acres, raised by a no-nonsense Dutch mother and an ambitious father who continues to build a fortune on powders, unguents and pills, Alma is a deeply curious child. “A right little dromedary, she was — tireless and uncomplaining. Never took ill. Stubborn. From the moment the girl learned to speak, she could not put an argument to rest. If her millstone of a mother had not steadfastly ground the impudence out of her, she might have turned out to be frankly rude. As it was, she was merely forceful.”

As life unfolds, there are those who whisper that “the Whittakers had rendered their girls completely unmarriageable, what with all that education.” But Alma and her sister, Prudence, are held to a higher standard than marriageability. Alma finds learning easy, natural, thrilling; her beautiful sister labors over it as if she were hammering stone. All the same, Prudence defies prediction and marries their stiff, waxen-faced tutor. Meanwhile, Alma, discovering her appetite for sex in furtive, auto-induced ecstasy, soon learns that the man she fancies — a young publisher of botanical prints and books — has chosen to marry her best friend.

Alma soldiers on alone, using her solitude to find strength and pursue knowledge, helping her father shape his pharmacological empire even as she writes scholarly articles and publishes books. Botanical life is endlessly rewarding, ever florescent. For years to come, it is a happy salve. But the life form that proves most instructive to her is ordinary moss.

Moss. The very substance in which her father packed specimens considered far more valuable: cinchona, nasturtiums, fuschias. Alma’s encounter with moss is surprising, climactic, divine: “There, rising no more than an inch above the surface of the boulder, she saw a great and tiny forest. Nothing moved within this mossy world. She peered at it so closely that she could smell it — dank and rich and old. Gently Alma pressed her hand into this tight little timberland. It compacted itself under her palm and then sprang back to form without complaint. . . . It appeared to have its own weather. . . . This was the entire world. This was bigger than a world. This was the firmament of the universe, as seen through one of William Herschel’s mighty telescopes. This was planetary and vast. These were ancient, unexplored galaxies, rolling forth in front of her.” Moss becomes Alma’s life obsession, and in time she writes a book, “The Complete Mosses of North America.”

When a prospective husband eventually presents himself — a beautiful and soulful man who draws orchids to perfection, although he is more than a little damaged — there are other lessons for Alma to learn.

“The Signature of All Things” is not, by any means, a seamless novel. There are moments of jarring prose, of nonsensical leaps, of characters going places you doubt they would ever go. But there are far more moments of transcendence, of Gilbert reaching — with absolute confidence — for a higher sphere.

Alma and her love will eventually find common ground in a 16th-century German shoemaker named Jacob Boehme, a naturalist who believed in something called the “signature of all things” — namely that God himself resided in every flower, leaf, fruit and tree. The natural world, in this reckoning, is written in divine code, and if we could fathom it, we would see proof of the Creator’s hand.

Gilbert has been a journalist, a biographer, short-story writer, novelist, memoirist and, perhaps most famously, a celebrated “Oprah author,” but she continues to set higher goals for herself. Like Victor Hugo or Émile Zola, she captures something important about the wider world in “The Signature of All Things”: a pivotal moment in history when progress defined us in concrete ways.

“It is exceedingly likely that my greatest success is behind me,” Gilbert once said about the phenomenon that brought her memoir “Eat, Pray, Love” 10 million readers in more than 30 languages around the world. She needn’t worry.

If life is reasonable — if the natural, Darwinian order is for strength to prevail and grit to triumph — then Alma will find love after all. And Gilbert will be lauded for following a runaway bestseller with a radiant novel.

Arana, a writer at large for The Post and former editor of Book World, is the author of “Bolivar: American Liberator” and the novel “Cellophane.”

On Oct. 7, Elizabeth Gilbert will be at the Sixth & I Synagogue, 600 I St. NW, Washington. For information about tickets, call Politics & Prose Bookstore at 202-364-1919.