A fortune in gunpowder would seem an unlikely foundation for a life of quiet scholarship. But the English diarist, and omnivorous scholar, John Evelyn (1620–1706), owed his leisure to the lucrative monopoly on the manufacture of the explosive that his great-grandfather had obtained two generations earlier. From such combustible origins, Evelyn would pursue a long career devoted to the satisfaction of obsessive curiosity. Best known for his diary, a classic of the genre, Evelyn in fact was an impassioned amateur of a peculiarly English sort. His personal motto, which he copied into all his books for 80 years, was “Explore Everything, Keep the Best.” It was the precept of a connoisseur and Evelyn followed it unswervingly.

John Evelyn might seem of interest only to specialists in 17thcentury manners. Nothing could be more mistaken. Not only does the fascination of the man himself grow with acquaintance, but his approach to life offers a tacit rebuke to our own. Compared to him, we look narrow in our interests. An extraordinary openness to life in all its manifestations was his defining feature. This becomes clear from reading Gillian Darley’s new biography, “John Evelyn: Living for Ingenuity” (Yale, 396 pages, $40). Beautifully written and adorned with superb illustrations, Ms. Darley’s book brings Evelyn into focus as never before. She had access to the large trove of unpublished Evelyn manuscripts deposited in the British Library in 1995. Working from these, rather than from the famous diary, she has brought a little-known man, and a vanished world, back to life.

Evelyn was 10 years old when he began keeping his diary. This was more than mere record-keeping. He was as acquisitive as he was inquisitive. Like the books or prints or botanical specimens he collected, the diary served as a cabinet in which his daily life was contained. And his varied interests always had a larger purpose, however Pickwickian they might at first seem. Indeed, a case could be made — and Ms. Darley makes it — that Evelyn had a visionary streak, as pragmatic as it was farseeing.

Thus, his quaintly titled “Fumifugium,” published in 1661, tackled the problem of air pollution. Evelyn was forceful, evoking a London with “her stately head in Clowds of Smoake and Sulfur, Stink and Darknesse.” As he realized, the pollution was caused by coal-burning, which leaves “a sooty crust” over everything, and he advocated a kind of proto-Green Belt of sweet-smelling herbs to surround and protect the city. A few years later, when the Great Fire devastated London, Evelyn was horrified by the damage but couldn’t resist observing that if his measures had been adopted, it “might have saved the burning of a Greate Citty.” His similar work on English forests, his love of gadgets (from a “perpetual motion” machine to a device for vacuum-sealing perishables), his involvement with his friend Christopher Wren in the renovation of St. Paul’s Cathedral, and above all, his genius as a designer of gardens, testify to his originality. So varied were Evelyn’s many interests that it has taken until the present to appreciate them at their full value.

Evelyn’s friendships were as wide-ranging as his pursuits. A close friend of Samuel Pepys, the greatest of all diarists, he knew everyone else worth knowing, from the scientists Robert Boyle and Robert Hooker to the poets Edmund Waller and Abraham Cowley. He stood with the aging Thomas Hobbes at a Paris window from which they observed the 13-year-old Louis XIV riding in cavalcade. On another occasion, Evelyn would have an audience with the Sun King himself. Ms. Darley shows us these figures as Evelyn would have seen and known them, and so they take on unexpected vividness in her account. But her best portrait, after Evelyn himself, is of Mary Evelyn, his wife. Raised in France, where Evelyn met her on his Grand Tour, Mary was only 12 when she became engaged. Their courtship and marriage played out against momentous events: in France, the revolt known as the Fronde, and in England, the execution of Charles I (which grieved Evelyn, a dedicated royalist), the English Civil War, the outbreak of plague and the ravages of the Great Fire. Their marriage lasted for 60 years; their affection and devotion to each other only deepened with age. Ms. Darley’s running portrayal of this long marriage, and of Mary Evelyn in all her sophistication, intelligence, and style, are perhaps the most impressive achievements of her biography.

Evelyn attributed his longevity and unfailing sprightliness of mind to his diet (he’d once written a treatise on salads). But a deeper factor was at work. When T.S. Eliot wrote that “old men should be explorers,” he could have had Evelyn in mind. Salad may have helped but it was curiosity that kept him young.

eormsby@nysun.com