Every year, immediately before Purim, my rabbi enjoins his congregation to attend the reading of the Megillah, intoning magisterially, “Remember to wear a funny hat. Don’t forget.” For him, this is the supreme mitzvah; visiting the sick, accompanying the dead, attending the bride, don’t even come close.

I am wracked by the need to discover the origins of this commandment. Finally, with the benefit of a scholarship from Bar Ilan University and the blessing of my wife ("take five years, take ten years; only don’t talk to me while I’m watching Master Chef"), I embark on the momentous task of assembling the evidence.

I begin with the Mishnah, where the dispute sets the School of Hillel against the School of Shammai. The enigmatic Hillelite statement: “The hat is not the issue” (Ha-Kova Hoo Lo Ha-Iqar) seems to have provoked unusually acrimonious clashes between the students of the two houses and resulted in broken heads.

Later, in the Babylonian Talmud, the veil is lifted. The majority hold that the hat needs to be intrinsically funny, i.e. the mere sight of it would cause the observer to titter, even if it were not on the head of the wearer.

By contrast, the minority led by Rabbi Yaakov argue (and this is surely Hillel’s point) that context is everything. For example I might don a policeman’s helmet together with a burglar’s vest composed of broad horizontal hoops. This would induce helpless laughter in the observer (granted, it would help if the observer was observing the other supreme Purim Mitzvah: to get legless).

So divided are the rabbis that they declare ‘Teyku’: ‘let the decision be made by Moshiach when he comes’.
The dispute re-emerges with renewed vigour in the 12th century when the Ramban takes exception to the section of Mishneh Torah where the author, the Rambam – without recourse to the sources – states that the Halakha is with Rabbi Yaakov. The Ramban immediately issues a Herem (an edict of excommunication) against the Rambam.

Confusion descends when the Rambam points out that the Ramban has spelt his name (the Rambam’s) with a Nun instead of a Mem and has consequently excommunicated himself (the Ramban). The Ramban is later to be found wandering distractedly through the streets of Cordoba whistling the Eton Boating Song.

Closer to our own time we know that the enigma of the funny hat obsessed Sigmund Freud. Freud would go on to write a study of the Book of Esther (The King Who Mistook His Wife For A Hat) in which he speculates that Ahasuerus married Esther, not because she was the most beautiful woman in his empire, but rather because she reminded him of his mother’s beanie.

My work begins to receive recognition from scholars from a multiplicity of disciplines and I am deluged with material. Ruth Chapeau, an historian of the American Labour movement in Newark, New Jersey draws my attention to the Lower East Side novelty hat workers strike of 1901 which prompted Rabbi Nossin Shtreimel of the Adath to issue an edict against the purchase of hats produced by blackleg operatives brought in to break the morale of the unionised labour force

The strain of following up so many loose strands starts to take its toll. My professor, Dr Naftali Tembel, fears for my sanity and insists that I return home to visit my wife. Now, on the verge of publishing my magnum opus, I learn that she has left me for the arms of Morris Lefkowitz, the eponymous owner of S Lefkowitz and Son, distributors of Ladies Millinery Trimmings.

My rabbi adjures me not to yield to bitterness. I have, he reassures me, succeeded in un-entangling one of the thorniest Halakhic problems of our epoch. “Take time out for yourself,” he urges, “visit some internet dating sites.” So here I am, sitting in the bar of the Tel Aviv Hilton waiting for one Trilby O’Ferrall to walk through the door. I suspect it’s a pseudonym. The only O’Ferrall I know is a Sadie…