Confronted with this difficulty, the Talmud advances a second theory: cherchez la femme. Yes, a woman must be responsible, the question is which one? Again, there are two theories.

1. The brothers quarreled over the woman in their life: Adam’s second wife and their mother, Eve. (And whatever Freud will have to say about Oedipus and the complex that bears his name will be nothing but commentary.)

2. The woman was none other than Abel’s twin sister, whom one source describes as having been the world’s most beautiful woman. Cain was determined to marry her. So was his young brother, which complicated matters. Cain invoked the right of seniority, Abel that of simultaneity: we were brought into the world together, said he, together we shall remain.

Thus, whether mother or sister, woman would be responsible for the first fratricidal war in history; because of a lover’s disappointment, Cain lost his soul, Abel his life and we, their fellow-men, our good conscience.

This theory will surely appeal to some. The trouble is that no reference to a sister can be found in Scripture. Surely the Bible could have managed to give her a name, an identity; it could even have asked her whether she had a preference between the two pretenders.

Was it their mother they coveted, after all? Here again the explanation is not satisfactory. Would Adam not have had something to say in the matter?

And so we come to the third and last possibility: that the conflict revolved around religion or at least matters of some spiritual concern. Since Cain and Abel had to share the universe, the older had chosen the here-and-now and his brother the world-to-come. However, Cain soon demanded more; namely, a share in the other world as well. When Abel refused to relinquish any part of it, Cain flew into a rage and killed him.

An image: the two brothers fought over the Temple in Jerusalem. Each wanted it for his own. The family quarrel would thus actually have been a religious war. A mystical motive, which paradoxically seems the most rational: Jerusalem has indeed continued to cause bloodshed throughout the centuries.

Unfortunately, here again manifold and varied objections and contradictions appear. In principle, the world-to-come was promised to all men and no one could exclude anyone else. Only God could decide whether to let Cain enter or not. Only God could open or close the celestial gates. And so Abel is thought to have overstepped his limits. As for the Temple, how could Abel even contemplate erecting it on his land, since, legally, he had none to call his own?

This last theory thus would place the blame on Abel, whose behavior was both unreasonable and unwarranted, rather than on Cain. Cain had every right to become annoyed. Abel really did go too far: he was taking advantage of his brother. He who owned not a parcel of land in the whole world, tried to claim the most precious of all to build the holiest edifice of all. Cain would not have been human had he not reacted with rage.