The most important source of plagiarized material was John Lawson's A New Voyage to Carolina (1709), initially printed in London as part of John Stevens's A New Collection of Voyages and Travels. A New Voyage provided an estimated 85 percent of the text for Brickell's Natural History; not only was the organization of the Natural History copied from Lawson, but whole sections of text were lifted out of A New Voyage and transposed, often verbatim, into Brickell's work. Additional important sources included John Clayton's "Letters" to the Royal Society of London, which appeared in the Philosophical Transactions in 1693-94; Thomas Harriot's A Briefe and True Report of the New Found Land of Virginia (1588); and John Ray's Ornithology of Francis Willughby, produced by the Royal Society in 1678.
Brickell also borrowed from multiple sources for the copperplate illustrations of animals and plants that graced his book as well as for the state map, the latter being a version of Edward Moseley's "A New and Correct Map of the Province of North Carolina" (1733). Most of the bird and fish plates were taken from John Ray's Ornithology of Francis Willughby and Historia Piscium, respectively, while many other animal plates were borrowed from Edward Topsell's The Historie of Foure-footed Beasts and The Historie of Serpents. Plant illustrations were derived from John Gerard's Herball and Nicholás Monardes's Primera y Segunda y Tercera.
Although Brickell's plagiarisms have been extensively delineated, few substantiated details have emerged about his life. His family background, dates and places of birth and death, and circumstances of his medical training remain unknown. Brickell apparently lived in North Carolina at least from 1729 to 1731, served as physician to Governor Richard Everard, was a member of the North Carolina Grand Jury, and testified before a committee of the Irish House of Commons in 1735-36 after his return to Ireland.