And if the above be the state of the case, how do Jews and Christians search after “the shadow of an ass,” in seeking to ascertain from those prophecies which they believe in common, whether He who was foretold has come, or has not yet arrived, and is still an object of expectation? But even suppose it be granted to Celsus that it was not Jesus who was announced by the prophets, then, even on such a hypothesis, the investigation of the sense of the prophetic writings is no search after “the shadow of an ass,” if He who was spoken of can be clearly pointed out, and it can be shown both what sort of person He was predicted to be, and what He was to do, and, if possible, when He was to arrive. But in the preceding pages we have already spoken on the point of Jesus being the individual who was foretold to be the Christ, quoting a few prophecies out of a larger number. Neither Jews nor Christians, then, are wrong in assuming that the prophets spoke under divine influence; but they are in error who form erroneous opinions respecting Him who was expected by the prophets to come, and whose person and character were made known in their “true discourses.”
Source: Against Celsus (New Advent)