Robert Calef (c. 1648–1723) was a cloth merchant in colonial Boston who came to America before 1688. He was the author of More Wonders of the Invisible World, a book composed throughout the mid-1690s denouncing the recent Salem witch trials of 1692-3 and particularly examining the influential role played by Cotton Mather.
Aside from More Wonders of the Invisible World, little is known about Robert Calef. From 1702-04, Calef was an overseer of the poor. In 1707 he was chosen an assessor, and in 1710 a tithingman, which he declined. He retired to Roxbury, where he was a selectman. He died there in 1722 or 1723, "aged about 45".
To defend the Salem witch trials, Cotton Mather published his account of the Salem witch trials, Wonders of the Invisible World: Being an Account of the Tryals of Several Witches, Lately Executed in New-England, in 1692, and his father Increase Mather published his own Cases of Conscience Concerning Evil Spirits the same year. Robert Calef, after exchanging several letters with Cotton Mather, published his book More Wonders of the Invisible World, deliberately referencing Cotton Mather's title. Calef objected to proceedings that lead to "a Biggotted Zeal, stirring up a Blind and most Bloody rage, not against Enemies, or Irreligious Proffligate Persons, But (in Judgment of Charity, and to view) against as Vertuous and Religious as any they have left behind them in this Country, which have suffered as Evil doers with the utmost extent of rigour". Aside from the preface and postscript, Calef begins and ends with Mather's accounts in his own words. He finished his compilation in 1697, but added a postscript before final publication.
Due to licensing and control over the printing press by Boston clergy, and particularly the Mathers, Calef's book was shipped to England to be published in 1700. Cotton Mather wrote in his diary, "It was highly rejoicing to us when we heard that our Booksellers were so well acquainted with the Integrity of our Pastors, as that not one of them could admit of any of those Libels to be vended in their shops."
Mather's father, Rev. Increase Mather, publicly burned the book in Harvard Yard. In 1701, Mather responded with Some Few Remarks upon a Scandalous Book, written in the plural with co-signers, but occasionally lapsing into first person. The opening lines suggest that Calef's book had been well received by the masses in New England, despite his inability to have it published there: "...that Scandalous Book... has made our worthy Pastors Obnoxious ... among an unguided multitude". Mather does not directly dispute the particulars of Calef's book but accuses Calef of being a follower of Satan, and uses select quotes from the Bible intended to put the merchant Calef in his place, including Exodus 22:28: "Thou Shalt Not Speak Evil of the Ruler of Thy People".