Whether Peringer even partially fulfilled the wish of his king is not known; probably he altogether failed in his mission. Some years later (1696–1697), two learned Swedes, probably also commissioned by Charles XI, traveled in Lithuania to visit Karaite communities and buy up their writings. At the same time they invited Karaites to visit Sweden, and give information respecting their doctrines. Zeal for conversion had certainly more share in the matter than curiosity about the unknown. A young Karaite, Samuel ben Aaron, who had settled at Poswol in Samogitia, and understood some Latin, resolved to make a journey to Riga, and hold a conference with John Puffendorf, a royal official. Through want of literary sources and the ignorance of the Karaites concerning the origin and development of their sect, Samuel ben Aaron could give only a scanty account in a work, the title of which proves that fancifulness had penetrated also to Karaite circles.
From another side the Karaites were the object of eager inquiry. A professor at Leyden, Jacob Trigland, fairly well acquainted with Hebrew literature, who intended to write a book about the old Jewish sects, no longer in existence, had his attention directed to the still existing Karaites. Inspired by the wish to get information concerning the Polish Karaites and obtain possession of their writings, he sent a letter with various questions through well-known mercantile houses to Karaites, to which he solicited an answer. This letter accidentally fell into the hands of a Karaite, Mordecai ben Nissan, at Luzk, a poor official of the community, who did not know enough to give the desired information as to the beginning and cause of the schism between Rabbanites and Karaites. He regarded it as a point of honor to avail himself of this opportunity to bring the forgotten Karaites to the remembrance of the educated world through the instrumentality of a Christian writer, and to deal blows at their opponents, the Rabbanite Jews. He spared no sacrifice to procure the few books by which he might be able to instruct himself and his correspondent Trigland. These materials, however, were not worth much, and Mordecai's dissertation for Trigland proved unsatisfactory, but for want of a better work it had the good fortune to serve during nearly a century and a half as the only source for the history of Karaism. Some years later, when Charles XII, the hero of the north, conquered Poland in his victorious career, and like his father was anxious to have more precise intelligence respecting Karaites, he also made inquiries concerning them. Mordecai ben Nissan used this occasion to compose a work in Hebrew for Charles XII, in which he freely indulged his hatred against Rabbanites, and strained every nerve to make Talmudical literature ridiculous.
The zealous attention paid by Christian scholars to Jewish literature could not fail to cause annoyance and inconvenience to Jews. They felt sorely burdened by German Protestant literati, who, acquiring cumbersome learning, strove to rival the Dutch writers and Richard Simon in France, without possessing their mild and gentle toleration towards Jews, or their elegance of style. Almost at the same time three German Hebraists, Wülfer, Wagenseil, and Eisenmenger, used their knowledge of Hebrew literature to bring accusations against the Jews. All three associated much with Jews, learned from them, and devoted much study to Jewish literature, mastering it to a certain degree.
John Wülfer of Nuremberg, who was educated for the church, and had studied with a Jew of Fürth and afterwards in Italy, thoroughly acquainting himself with biblical and Talmudical literature, sought after Hebrew manuscripts and old Jewish prayer-books to found an accusation against the Jews. Christians, instigated by baptized Jews, took offense at a beautiful prayer (Alenu), which arose in a time and country in which Christianity was little known. Some Jews were wont to add a sentence to this prayer: "For they (the heathen) pray unto vanity and emptiness." In the word "emptiness," enemies of the Jews pretended to see an allusion to Jesus and to find blasphemy against him. The sentence was not printed in the prayer-books, but in many copies a blank space was left for it. This vacant space, or the presence of the obnoxious word, equally enraged the Protestants, and Wülfer, therefore, searched libraries to find authority for it, and when he found the word in manuscripts, he did not fail to publish his discovery. He praised Prince George of Hesse because he made his Jews swear an oath never to utter a blasphemous word against Jesus, and threatened to punish them with death in case of transgression. Wülfer, on the other hand, was candid enough to confess that the Jews had been long and cruelly persecuted by Christians, that the accusation against them of using blood was a mischievous invention, and that the testimony of baptized Jews deserved little credence.
John Christopher Wagenseil, a lawyer and professor at Altorf, was a good-hearted man, and kindly disposed towards the Jews. He had traveled farther than Wülfer, had penetrated through Spain into Africa, and took the greatest pains to hunt up such Jewish writings as attacked Christianity from the ground of Holy Scripture or with the weapons of reason. His discoveries filled his quiver "with the fiery darts of Satan." Wagenseil looked up that insipid compilation of the magical miracles of Jesus (Toldoth Jesho), with which a Jew, who had been persecuted by Christians, tried to revenge himself on the founder of Christianity, and he spent much money in hunting up this Hebrew parody of the Gospel. Few Jews possessed copies of it, and the owners kept them under lock and key for their own security. Because one Jew had once written these absurdities about Jesus, and some Jews had copies of the book in their possession, while others had defended themselves against attacks by Christians, Wagenseil felt assured that the Jews of his time were vile blasphemers of Jesus. He therefore implored the princes and civil magistrates to forbid the Jews most strictly to continue such blasphemy. He directed a pamphlet, "The Christian Denunciation," to all high potentates, urging them to impose a formal oath upon Jews, not to utter any word of mockery against Jesus, Mary, the cross, the mass, and other Christian sacraments. Wagenseil had two pious wishes besides. One was that the Protestant princes should take active steps for the conversion of the Jews. He had, it is true, convinced himself that at Rome, where since the time of Pope Gregory XIII a Dominican monk was wont on certain Sabbaths to hold forth, in a sleepy manner, before a number of Jews, they either ignored him or mocked at him. But he thought that the Protestant princes, more zealous Christians than the Catholics, ought to devise a better plan. It also grieved this thorough scholar that the colleges of rabbis presumed to criticise writings concerning the Jewish religion, and that they ventured to express their approval or disapproval; this was an infringement of the rights and the dignity of Christians! Withal Wagenseil, as has been said, was kindly disposed to the Jews. He remarked with emphasis that he thought it wrong and unworthy to burn Jews, to rob them of all their property, or to drive them with their wives and children out of the country. It was excessively cruel that in Germany and other countries children of Jews should be baptized against the will of their parents, and compelled to accept Christianity. The oppressions and insults to which they were exposed at the hands of the Christian rabble were by no means to be approved. It was not right that they were compelled to say "Christ is risen," that they were assailed with blows, had dirt and stones thrown at them, and were not allowed to go about in safety. Wagenseil wrote a pamphlet to expose the horrible falsehood of the charge, that the Jews use the blood of Christians. For the sake of this pamphlet, which spoke so warmly for the Jews, his other absurdities should be pardoned. Wagenseil expressed his indignation at the horrible lie:
"It might pass if the matter stopped with idle gossip; but that on account of this execrable falsehood Jews have been tormented, punished, and executed by thousands, should have moved even stones to compassion, and made them cry out."
Is it credible that in the face of this judgment, spoken with firm conviction by Wülfer and Wagenseil, who not only had associated with Jews for years, but were accurately acquainted with Jewish literature, and had penetrated into its innermost recesses as none before them, their contemporaries should seriously revive the horrible falsehood, and justify it with ostentatious learning? A Protestant, John Andrew Eisenmenger, professor of Oriental languages, repeated the accusation, a thousand times branded as false, and furnished posterity with abundant material for charges against the Jews. Eisenmenger belonged to the class of insects which sucks poison even out of flowers. In confidential converse with Jews, pretending that he desired to be converted to Judaism, and in the profound study of their literature, which he learned from them, he sought only the dark side of both.
He compiled a venomous book in two volumes, the title of which in itself was an invitation to Christians to massacre the Jews, and was synonymous with a repetition of earlier scenes of horror for the Jews.
"Judaism Unmasked; or a Thorough and True Account of the Way in which the Stubborn Jews frightfully blaspheme and dishonor the Holy Trinity, revile the Holy Mother of Christ, mockingly criticise the New Testament, the Evangelists, the Apostles, and the Christian Religion, and despise and curse to the Uttermost Extreme the whole of Christianity. Much else besides, either not at all or very little known, and Gross Errors of the Jewish Religion and Theology, as well as Ridiculous and Amusing Stories, herein appear. All proved from their own Books. Written for the Honest Information of all Christians."