The solar calendar proposal for the Last Supper
A solar calendar offers one proposed way to reconcile the different Gospel accounts of the Last Supper. In this explanation, the disagreement concerns how the date of Passover was calculated rather than when the meal took place. Jonathan Klawans discusses the proposal but does not accept it as an established solution. His objection begins with a practical historical question: where is the record of Passover being celebrated twice in the same place? The proposal needs that possibility to do real explanatory work. An appealing reconciliation still has to account for what it would mean for the celebrations themselves.
The Gospel accounts provide the starting point. Matthew, Mark and Luke place the Last Supper after the Jewish holiday had begun. John places the beginning of the seven-day Passover festival after Jesus is crucified. That difference is the reason a reconciliation is being sought. It is useful to keep the accounts separate before trying to bring them together. A proposal about calendars is an interpretation of their relationship, rather than another description of the meal. The question is whether that interpretation supplies enough support to bridge the difference in timing that Klawans identifies between John and the other accounts.
Annie Jaubert presents the calendar theory in The Date of the Last Supper, published in 1965. The proposal substitutes a disagreement over calculation for a disagreement over the occasion itself. One reckoning would follow a solar calendar, while another would follow a lunar one. That distinction explains the attraction of the idea: the accounts might be describing the same occasion through different systems. But the attraction is only the beginning of the argument. Klawans asks what else would have to be true for the reconciliation to function. His discussion moves from the proposed explanation to the historical circumstances that explanation requires.
The first difficulty is the implied duplication of Passover. Klawans finds it difficult to conceive of the festival being celebrated twice in the same place without a contemporary or even a later writer mentioning it. Two celebrations in the same week would, in his assessment, have been remarkable. This is an objection about missing testimony, and it should be described with that limit intact. He is not offering a surviving account of duplicate celebrations and disputing its details. He is asking why the event needed by the proposal has no identified record in the discussion. That absence is central to his reluctance to accept the reconciliation.
The next difficulty concerns the workings of the calendars. Klawans notes that solar calendars are known from the Book of Jubilees and the Temple Scroll, while also saying that their precise operation is not known. The existence of a solar calendar therefore leaves another question open: how would it have remained aligned in the way the proposal requires? Naming a system does not settle the details of its use. The argument needs those details because the proposed reconciliation depends on calendars that could both be functioning while placing the occasion only a few days apart. That is a more specific requirement than the existence of different calendars.
Jubilees supplies the sharpest example. Its calendar explicitly prohibits intercalation, the addition of extra days in a leap year. Klawans describes it as a 364-day solar calendar and argues that, without intercalation, it would have been displaced by months by the time of Jesus. The concern in that argument is the size of the displacement. A difference of months cannot simply be treated as the difference of a few days required by the reconciliation. The calendar's stated prohibition matters because the adjustment that might help the proposal is precisely the adjustment that Jubilees excludes. This makes the calendar mechanism part of the historical question.
To reach the possibility of two functioning calendars separated by only a few days, Klawans says some manner of intercalation must be hypothesized. That is an additional assumption, rather than a detail he presents as established. The distinction gives the discussion its measured conclusion. Jaubert's book presents what he calls a good theory, but it remains a theory. The proposal has an intelligible purpose, and the objections concern the support required to carry out that purpose. Keeping the assumption visible makes the argument easier to assess without turning a possible reconciliation into a settled account of what happened.
The strongest reading keeps all of those questions together. The Gospel timing differs; the proposed reconciliation invokes different calculations; duplicate celebrations lack an identified record; and the calendars' operation leaves an unresolved adjustment problem. Each point addresses a different part of the same proposal. The answer to the opening puzzle is therefore the missing testimony about two celebrations, with the calendar objection adding another layer. This discussion does not require a sweeping conclusion about every aspect of the Last Supper. It offers a narrower judgment about whether this particular reconciliation has enough historical support to be accepted.