The Cambridge History of English and American Literature in 18 Volumes (1907–21).
Volume II. The End of the Middle Ages.
§ 10. Mandeville’s Detail
The author dovetails his bits of genuine information into his fictions with deft ingenuity. One of the means of proving a diamond is to “take [char]e adamaund that drawez [char]e nedill til him by [char]e whilk schippe men er governed in [char]e sea” (Egerton), and, if the diamond is good, the adamant, “that is the schipmannes ston” (Cotton) will not act upon the needle while the gem rests upon it. But Mandeville cannot refrain from heightening the marvellous stories culled elsewhere. To the account of the diamond, sufficiently strange in “Ysidre” or “Bertilmew,” to whose corroboration he appeals, he must needs add that “[char]ai growe sammen, male and female, and [char]ai er nurischt with dew of heven … and bringes furth smale childer and so [char]ai multiply and growez all way” (Egerton). He has often seen that they increase in size yearly, if taken up by the roots with a bit of the rock they grow on and often wetted with May dew. The source of this detail, as of the stories of Athanasius, of the man who environed the earth and of the hole in the Ark “whare the fend [char]ode out” when Noe said Benedicite, has not yet been discovered. Probably Mandeville invented them, as he did the details of the Great Cham’s court: hangings of red leather, said Odoric—hangings made of panther skins as red as blood, says Mandeville; now, a panther, in those times, was reckoned a beast of unheard-of beauty and magical properties. Odoric expressly owned that he did not find such wonders in Prester John’s land as he had expected from rumour; Mandeville declares that the half had not been reported, but that he will be chary of what he relates, for nobody would believe him. Such indications of a becoming reticence help to create the air of moderation which, somehow, pervades the book. The author’s tone is never loud, his illustrations are pitched on a homelier key than the marvel he is describing—so of the crocodiles, “whan thei gon bi places that ben gravelly it semethe as thoughe men hadde drawen a gret tree thorghe the gravelly places” (Cotton). It is a blemish on the grandeur of the Cham’s court that “the comouns there 
ten withouten clothe upon here knees.” Mandeville faces the probability that his readers may withhold belief: “hepat will trowe it, trowe it; and he pat will no[char]t, lefe. For I will never [char]e latter tell sum what pat I save … wheder [char]ai will trowe it or [char]ai nil” (Egerton). He discounts a possible comparison with Odoric by mentioning that two of his company in the valley of devils were “frere menoures of Lombardye,” and artfully calls to witness the very book that he stole from, “the Lapidary that many mean knowen noght.” Not that he ever avowedly quotes, save, rather inaccurately, from the Scriptures. The necessary conventional dress of orthodoxy he supplies to his travels by the device of crediting the mysterious eastern courts with holding certain Christian tenets. The Shrine of St. Thomas is visited “als comounly and with als gret devocioun as Cristene men gon to Seynt James” (Odoric said, St. Peter’s); Prester John’s people know the Paternoster and consecrate the host.
Mandeville hopes that everyone will be converted; his tolerance of strange creeds and manners is that of a gentle, not of a careless, mind. The Soudan of Egypt—who, indeed, rebuked the vices of Christianity after the fashion of Scott’s Saladin—would have wedded him to a princess, had he but changed his faith. “But I thanke God I had no wille to don it for no thing that he behighten me” (Cotton). It is with such light touches that Sir John pictures himself. He is no egoist, nor braggart; we know nothing of his appearance; he does no deeds of prowess himself “for myn unable suffisance”; his religion is that of ordinary men. He ventured, duly shriven and crossed, down the perilous vale, full of treasure and haunted by devils,
Sir, John, in short, reveals himself as a gentleman, filled with a simple curiosity and with that love of strange travel which, he says, is native to Englishmen, born under the moon, the planet which moves round the world so much more quickly than the others. He is honest and broad-minded, free from any taint of greed—there is not a sordid observation in the whole book—and that he ever comes to an end is due to his consideration for others, for were he to tell all he had seen nothing would be left for other travellers to say: “Wherfore I wole holde me stille.”