The book is Crossan's reduction of the authentic sayings of Jesus (according to his hermeneutic), and the outgrowth of his rather magisterial study: The Historical Jesus: The Life of a Mediterranean Peasant. That book, of course, both presumes and establishes the historicity of Jesus of Nazareth. But in his prologue to The Essential Jesus, Crossan provides a succinct refutation to the claim that there is no evidence, outside the gospels, of this man's existence.
If no Christian had written anything about Jesus for the first hundred years after his death, we would still have two succinct accounts from those not counted among his followers. One account dates from the last decade of the first century and comes from the Jewish historian Flavius Josephus in his Jewish Antiquities 18.63:John Dominic Crossan,The Essential Jesus (HarperSanFrancisco 1994, pp. vi-vii)
"About this time there lived Jesus, a wise man. . . . For he was one who wrought surprising feats and was a teacher of such people as accept the truth gladly. He won over many Jews and many of the Greeks. . . . When Pilate, upon hearing him accused by men of the highest standing amongst us, had condemned him to be crucified, those who had in the firstplace come to love him did not give up their affection for him. . . . And the tribe of the Christians, so called after him, has still to this day not disappeared."
His description is carefully neutral or, at most, mildly critical. The text was both preserved and interpolated by Christian editors, but I cite it without their proposed improvements.
The next account dates from the first decades of the sec-ond century and comes from the pagan historian Cornelius Tacitus. Having told how a rumor blamed Nero for the disastrous fire that swept Rome in 64 C.E., he continues in Annals 15-44:
"Therefore to scotch the rumour, Nero substituted as culprits, and punished with the utmost refinements of cruelty, a class of men, loathed for their vices, whom the crowd styled Christians. Christus, the founder of the name, had undergone the death penalty in the reign of Tiberius, by sentence of the procurator Pontius Pilatus, and the pernicious superstition was checked for the moment, only to break out once more, not merely in Judaea, the home of the disease, but in the capital itself, where all things horrible or shameful in the wor1d collect and find a vogue."
Despite the differences between the studied impartiality of Josephus and the sneering partiality of Tacitus, they agree on three rather basic facts. First, there was some sort of a movement connected with Jesus. Second, he was executed by official authority presumably to stop the movement. Third, rather than being stopped, the movement continued to spread.
There remain, therefore, these three: movement, execution, continuation. But the greatest of these is continuation.
If, after all, it is all invention, it had to be invented by someone. It had to have a focal point, an origination, a beginning. Scholars have long stopped debating the existence of Jesus of Nazareth. Now they discuss the life he lead (Crossan's books are excellent on this point), and the words he actually said.