The mystical element in this philosophy enabled some minds to find a home for the theurgy which had been increased by the importation of eastern ideas.(135) They form as it were the connecting link with the fourth religious tendency, which manifested itself in the craving for a communication from the world invisible, which found its satisfaction in magic and in a spirit of fanaticism. Some of these fanatics were doubtless also impostors;(136) but some were high-minded men struggling after truth, of whom possibly an example is seen at an early period in Apollonius of Tyana; deceived rather than deceivers. This tendency operated in some minds to cause them to reduce Christianity to ordinary magic and prodigies; while among a few it created yearnings for a nobler satisfaction, which drew them toward Christianity, as in the case of the Clemens, whose autobiography professes to be given in the well-known work of the early ages, the Clementines. (11) Such seem to have been the chief forms of religious thought existing among the heathen to whom Christianity presented itself, on which were founded the preparation of heart which led to the acceptance of its message, or the prejudices which rejected its claims;—viz. among the masses, a sensuous unintelligent belief in polytheism;—among the educated, disorganization of belief; either materialism, the total rejection of the supernatural, and a political attachment on the principle of expedience to existing creeds; or philosophy, ethical, dualistic, pantheistic, despising religions as mere organic products of national thought, and trying to seize the central truths of which they were the expression; or a mystical craving after the supernatural, degrading its victims into fanatics. The further analysis of these tendencies would show their connexion with the threefold classification before given of the tests of truth into sense, reason, and feeling. We have thus prepared the way for interpreting the lines of argument used in opposition to Christianity, and shall now proceed to sketch in chronological succession the history of the chief intellectual attacks made by unbelievers. It is not until the middle of the second century that we find Christianity becoming the subject of literary investigation. Incidental expressions either of scorn or of misapprehension form the sole allusions in the heathen writers of earlier date (12); but in the reigns of the Antonines, the Christians began to attract notice and to meet with criticism. We read of a work written against Christianity by a Cynic, Crescens, in the reign of Antoninus Pius;(137) and of another by the tutor of Marcus Aurelius, Fronto of Cirta,(138) in which probably the imperial persecution was justified.