A long-lost book-length guide to “manly health” by Walt Whitman, in which the great American poet tackles everything from virility to “care of the feet” and the attainment of a “nobler physique”, has been rediscovered by a scholar, more than 150 years after it was first published under a pen-name.

Written under the pseudonym Mose Velsor, a known pen-name for Whitman, the 13-part Manly Health and Training series was published in the New York Atlas in 1858 and runs to nearly 50,000 words. Zachary Turpin from the University of Houston stumbled across it when searching digital archives for Whitman’s pseudonyms, and finding a single hit for “Mose Velsor” in the NY Tribune, advertising the fact that his “original articles on manly training” were shortly to appear in the New York Atlas. He sent away for the Atlas microfilm, and was astonished to discover the 13-instalment series.

The New York Atlas’s trail advertisement for Whitman’s Manly Training.

Photograph: American Antiquarian Society and the Walt Whitman Quarterly Review

“When I started investigating, I was completely unaware that such a series might exist. Scholars have long known that, among his mountains of notebook jottings and unpublished manuscripts, Whitman had scribbled out a pair of handwritten advertisements for a ‘first-class Original Work on Manly Training’. But whether or not such a thing had ever come to be, no one knew,” said Turpin. “It took about a day and a night for it to really hit me hard just what this was, in essence: a lost book, and a most unusual one, by Walt Whitman himself.”

Verifying Whitman’s authorship took a matter of minutes, said Turpin – not only was the pen name “one of Whitman’s go-to’s”, but “language appearing in Manly Health and Training matches word-for-word some jottings in Whitman’s notebooks about physique, health, and exercise. So that was that. In literary research, open-and-shut cases like this are unusual, to say the least.”

The entire text of Manly Health and Training is published online for free on Saturday in the new issue of the Walt Whitman Quarterly Review. Editor Ed Folsom, a professor at the University of Iowa, writes in an introductory note that the remarkable find will “alter the course of Whitman scholarship and biography”.

To you, clerk, literary man, sedentary person, man of fortune, idler, the same advice. Up! … Out in the morning! Walt Whitman, Manly Health and Training

In the journal, Turpin says the work can be seen as “an essay on male beauty, a chauvinistic screed, a sports memoir, a eugenics manifesto, a description of New York daily life, an anecdotal history of longevity, or a pseudoscientific tract”, and warns that it can be “eyebrow-raising”. “Readers should prepare to encounter a more-than-typically self-contradictory Whitman; his primary claims tilt from visionary to reactionary, commonsensical to nonsensical, egalitarian to racist, pacific to bloodthirsty – and back again,” he says.

“Guard your manly power, your health and strength, from all hurts and violations,” urges Whitman in one article. “This is the most sacred charge you will ever have in your keeping. To you, clerk, literary man, sedentary person, man of fortune, idler, the same advice. Up! The world (perhaps you now look upon it with pallid and disgusted eyes) is full of zest and beauty for you, if you approach it in the right spirit! Out in the morning!”

The poet also expounds his “deeply felt conviction, the result of much observation in New York, Brooklyn, and other cities, that the only true and profitable way of reaching the morals of the young is through making them first healthy, clean-blooded and vigorous specimens of men”.

Rowing, he advises, “is a noble and manly exercise; it develops the whole of the body. To many, the hunter’s excursion, with dog and gun, will prove salutary. The fishing jaunt the same. ‘Hurling’ is also a noble game, and calculated, if made popular, to help with the rest in producing a noble race of men.”

Self-help culture might feel like a “relatively new concept”, said Turpin, but Whitman’s articles prove “that these elements of our culture are much, much older than they might seem … They were already well established even in 1858 – Whitman certainly didn’t invent them.”

Facebook Twitter Pinterest ‘To many, the hunter’s excursion, with dog and gun, will prove salutary. The fishing jaunt the same’ ... Whitman fishing with friends, circa 1863. Photograph: Western Reserve Historical Society, Cleveland, Ohio

The series of articles sees Whitman state his theory that “America has mentality enough, but needs a far nobler physique”, and that “there is no doubt, as things now are, among the young men of modern civilised life, in cities, that a healthy manly virility seems to be almost lost – seems to have given place to a morbid, almost insane, pursuit of women, especially of the lowest ranges of them, for the mere repetition of the sensual pleasure.

“A man that exhausts himself continually among women is not fit to be, and cannot be, the father of sound and manly children,” he advises. “They will be puny and scrofulous – a torment to themselves and to those who have the charge of them.”

And Whitman advocates excluding almost everything but meat from the diet. “In our view, if nine-tenths of all the various culinary preparations and combinations, vegetables, pastry, soups, stews, sweets, baked dishes, salads, things fried in grease, and all the vast array of confections, creams, pies, jellies, &c, were utterly swept aside from the habitual eating of the people, and a simple meat diet substituted in their place – we will be candid about it, and say in plain words, an almost exclusive meat diet – the result would be greatly, very greatly, in favour of that noble-bodied, pure-blooded and superior race we have had a leaning toward, in these articles of ours”.

Folsom, calling the find “a really important and authentic discovery”, said the articles appeared halfway between the second edition of Whitman’s life work, Leaves of Grass, in 1856, and the 1860 third edition, which contained his Calamus poems. Exploring affection between men, they are “poems that have come to be read as the first articulation of gay identity and the first creation of a diction of male-male love,” said the professor. “Many writers have commented about how, after the Calamus poems, men suddenly had a language of love for other men. He was writing those poems at just the time he was writing Manly Health, which is, after all, a kind of hymn to the male body.”

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Folsom expects that more lost works by Whitman will be found, “whether published or in manuscript form, in digital archives or dusty trunks”..

“There are new Whitman finds every year – letters and newspaper articles and reprints of his poetry and fiction in places we would not have expected,” he said. “Occasionally … a new poem is discovered. He was a wildly prolific writer, and he called himself, in one late poem, ‘garrulous to the very last’. Well, he has been true to his word – he keeps talking, even in 2016, and now, suddenly, we have nearly 50,000 of his words that we didn’t have before.”