Greenleaf begins his book by arguing for the need to suspend prejudices and to be open to conviction, "to follow the truth wherever it may lead us" (p. 1). He cites Bishop Daniel Wilson's "Evidences" by stating that Christianity does not "bring irresistible evidence" but offers sufficient evidences for "the serious inquirer" (p. 2). He limits the scope of his book to an inquiry "to the testimony of the Four Evangelists, bringing their narratives to the tests to which other evidence is subjected in human tribunals" (p. 2). His specific inquiry is concerned with testing "the veracity of these witnesses by the same rules and means" employed in human tribunals (p. 3). Greenleaf argues the case by first inquiring as to the genuineness of the four gospels as ancient writings. Here he applies what is known in law as the ancient documents rule, stating that "Every document, apparently ancient, coming from the proper repository or custody, and bearing on its face no evident marks of forgery, the law presumes to be genuine, and devolves on the opposing party the burden of proving it to be otherwise" (p. 7). Greenleaf maintains that the Four Gospels do not bear any marks of being forgeries and the oldest extant copies may be received into court as genuine documents.