In the late tenth century the elders of the Jewish community of Kairouan (in present-day Tunisia) were perplexed by developments that had arisen in their city. Reports were circulating about persons with who were able to perform some amazing feats.
The powers attributed to those heroes included the ability to make themselves invisible when pursued by bandits, and even to render their attackers immobile. By pelting them with leaves or shards inscribed with appropriate divine names or spells, they could create protective force-fields to repel the assailants. By tossing an amulet into the water, a proficient wonderworker could calm a raging sea.
There were also some persons who knew how to access information about the future. They did this by means of “dream questions”; after an intense regimen of spiritual preparation, which involved the avoidance of meat or wine, and spending the night in a “pure place,” their dreams would be visited by mystic guides who referred them to scriptural texts that contained answers to the problems that were perplexing them.
Yet another super power that was demonstrated by wonder-workers in Kairouan was that of “ḳefiṣat derekh” whereby certain individuals could beam themselves faster than a speeding bullet across vast distances. Iberian Jews proudly recalled how their pedigree for talmudic scholarship could be traced back to a miraculous visit by the ninth-century Babylonian Gaon Natronai bar Hilai who had teleported himself from Babylonia to Spain to instruct them, and then instantly returned home to Iraq, although no one observed him journeying in any scheduled caravan.
In search of guidance about the correct attitude to adopt toward such supernatural phenomena, the Kairouanese Jews sought counsel from the most prominent rabbinic authority of the day, the Babylonian Gaon Rav Hai. In a responsum whose full text has not come down to us, the Gaon dismissed the reports as idle chatter and fake news, and assured his correspondents that even the most saintly and righteous persons are not able to contravene the laws of nature.
Two generations later, around the year 1006, the Jews of Kairouan were impelled to revisit the issue, posting a new query to Rav Hai (who lived to the age of ninety-nine years) in which they voiced their dissatisfaction with his previous reply and tried to make a stronger case for the veracity of the reports about the wonderworkers. For the most part they seemed to be relying heavily on the second-hand reports from outsiders—“several scholars from the land of Israel and from the land of ‘Edom’ [i.e., Christian Europe]”—who claimed that such marvels had been performed in full public view.
Faced with the objections to his original responsum, Rav Hai Gaon remained undeterred in his disparagement of the naïve attitudes demonstrated by his questioners. He expressed his incredulity that any intelligent person could be taken in by such tall tales. Furthermore, he attested that his predecessors had thoroughly investigated many of the miraculous claims and found them to be unsubstantiated, even though some of the purported events were not entirely beyond the bounds of credibility. He noted that the tale of Rav Natronai’s magical jaunt to Spain was unknown in Babylonia, and suggested that an imposter might have been impersonating him. To those who uncritically believed and spread those fantastic legends he applied the words of the Book of Proverbs, “the simple believeth every word.”
An extensive literature was available of magical instruction manuals that specified which divine or angelic names should be invoked to achieve a particular objective. To be sure, pious sages were exceedingly wary about following those manuals, since they could have hazardous side-effects for a practitioner who did not achieve a satisfactory level of spiritual purity. They could lead to blindness or even death. But these risks did not deter people from making use of those spells. On the contrary, they asked for more detailed instructions as to how to use them safely.
Rav Hai offered some intriguing methodological guidelines for assessing such claims in a scientific manner.
Central to his argument was the need to clearly distinguish between the real “signs and wonders” that were invoked by biblical prophets, and the lesser acts of legerdemain that can be performed by mere magicians. Serious miracles entail the total suspension or reversal of the natural order on a cosmic scale in ways that cannot be accomplished by any being except the Creator himself. Their purpose is to authenticate the divine origin of a prophet’s message.
Indeed, such signs must occur very infrequently if they are to be effective; for otherwise they would come to be perceived as natural phenomena, albeit unusual ones. Thus (to cite Rav Hai’s own example) if the righteous could cause the sun to reverse its daily course, then such reversals would become nothing more than minor astronomical anomalies, and would no longer serve to confirm the prophets’ credentials as emissaries of the Almighty.
Another condition that Rav Hai posited for a miracle story to be credible was that it not violate fundamental scientific or logical principles. This led him to a fascinating analysis of the stories about invisibility spells.
When you think about it, there are several different ways not to be seen. Perhaps the easiest to explain is that of blinding people or otherwise disabling their eyesight (I am reminded of the old pulp hero the Shadow who learned to hypnotically “cloud men’s minds” so that they could not see him). Rav Hai concedes that this form of invisibility is not altogether unbelievable.
However, as the claim to invisibility gets more narrowly defined, its credibility becomes more questionable. Thus Rav Hai hypothesized a tale about two men of similar size and build who are standing next to each other, but only the one who utters a magical name becomes invisible to an observer. The Gaon compares this to the case of a person who claims to clearly see tiny insects far away, but not the elephant and camel right in front of his eyes. No sane person would believe such a tale even if it were accompanied by a claim that God was directly filtering their vision. By the same token, if somebody next to you insists that he can observe a figure standing right in front of you, whereas you see nobody there at all, then you may be reasonably certain that you are being scammed after the manner of the naked emperor in the Andersen tale, or the president who thought he witnessed history’s largest inauguration audience. Rav Hai did however allow for the existence of bodies that are not solid, but composed of an ethereal transparent substance outside the normal range of human vision. Such, he believed, were the bodies of angels which could be rendered visible only to select individuals whose eyesight was divinely upgraded.
I find it illuminating to realize that there is scarcely a single point in Rav Hai Gaon’s listing of implausible tricks that cannot be easily achieved or explained today by standard science or with the help of a smartphone camera. We can easily blind attackers with a dose of pepper spray, distinguish between physiological myopia and hyperopia, or identify otherwise invisible objects by means of ultraviolet or infrared light. Modern cameras know how to “bokeh,” to blur figures into the background and focus attention upon the main subject.
Arthur C. Clarke observed that "any sufficiently advanced technology is indistinguishable from magic." We are indeed living in magical—though not necessarily miraculous— times.