Robert Calef, though probably not in advance of many others in detecting and dissenting mentally from the public errors of faith and practice in relation to witchcraft, was first to manifest nerve enough to speak out boldly his own thoughts and those of many others. Backed and aided probably by strong and learned men, he became to Christendom's witchcraft, as Martin Luther had been to its Roman creeds and practices, a bold, outspoken _protestant_. Each of them dared to brave strong currents of popular beliefs and practices, even when the course was encompassed with dangers. Each probably was moved and sustained by firm conviction that truth, right, and justice were on his side; each had nerve enough to stand firm and resolute in his self-chosen post of danger and philanthropy; and each was, to great extent, successful. Luther challenged the pope and his devotees to justify portions of their creed and practices, and Calef did the same to Cotton Mather, as a leading annunciator and expounder of the witchcraft creed. Luther and Calef each conceded that much in the creed of those whom he contested was founded on Scripture, and so far was impregnable; but they saw that many unauthorized and baneful appendages had been put upon true scriptural faith and instructions, and each labored to sever the true and good from the false and bad with which the currents of opinions and events had long been investing them. Neither of them, however, discerned all the errors and pernicious practices which have since become visible. Luther, though he saw, or at least heard, and scolded, and threw his ink-horn at Catholicism's devil, did not discard, but retained, in his Protestant creed, both him and witchcraft as they then existed in the Catholic belief. Calef conceded the positive existence of Mather's great personal witchcraft devil of supernal origin, vast power, and ever-burning malignity, but found him commissioned only by God--never by human witches, as it was then generally believed he was and must be, when he manifested his power through or upon man. We are much in doubt as to whether Calef was properly _author_ of a large part of what he published relating to witchcraft. The articles he put forth from time to time seem to us very varied in style and in merits as to their scholarly and rhetorical airs. It is said, in vol. i. p. 288, Mass. Hist. Soc. Records, that "Calef was furnished with materials for his work by Mr. Brattle of Cambridge, and his brother of Boston, and other gentlemen who were opposed to the Salem proceedings." He may have had--and we conjecture that he had--much help in putting his materials into the form in which they came before the public. We are able to learn very little concerning the man himself. It is usual to style him a Boston merchant, but Mather alludes to him as that "weaver," &c.