Hi Grrr82CU ~ welcome to the forum
... First the premise ... that Leonardo deliberately omitted painting a "goblet/cup/chalice/etc" .... This absent vessel, it is argued by Dan Brown ... was intended by Leonardo to provide future validation of the premise that the so-called "Holy Grail" is not a vessel but the descendant(s) of Jesus and Mary M.
Well, it is a theory ~ and I think that he is not the only person to put it forward. However, there is also here a supposition that the 'holy grail' actually attended The Last Supper.
With an imaginative eye perhaps even Leonardo himself did not have, many now see in the space between Jesus and the figure on his right a "V", deliberately painted in such a way to represent the female womb. ...
Renaissance paintings were often full of symbolism and this 'V' shape is rather obvious and encourages viewers tp wonfder about its meaning.
Leonardo painted this work almost fifteen hundred years after the event so what was his source of "information" about the subject of his painting? After all, he was not there and knew no one that was?
Of course Leonardo wasn't there, but his paintings do tend to make us think and question ~ and, in those days, documents from the East were turning up in the West and making people wonder about early Christianity.
Did he know or suspect something secret about Jesus?
I don't know.
...the picture portrays a "glass" with a liquid .. near each of those seated at the table. While such vessels holding water or wine may have graced tables in Leonardo's time, they certainly did not in the time of Jesus.
I would like to hope that anyone seriously studying the painting would realise that it owes a lot to Leonardo's own life and times. It supposedly reflects the holy land of Jesus's time, but actually reflects Renaiassance 'Italy'.
Evidence of “hollow” glassware (vases) date from the sixteenth century B.C.E., ...
I found some pictures of apparently Roman glasses:
... Why were they there? ?? What was so special that Jesus had planned for a long time to gather with his disciples on that night for that meal ??? Does any of that matter in relation to the issue of Leonardo's painting and the intense debate over "The Da Vinci Code" ??
The meal was to commemorate Passover !!
Why is that significant?
The Passover of Moses had two things in common with the Passover of Jesus and the last meal with his disciples (1) the "bread-of-haste" (unleavened bread) and (2) wine. That night was to commemorate the flight of the Israelites from Egypt, not to set the stage for the going forth of Jesus' seed carried by a pregnant Mary M. as the premise of Mr. Brown and those embracing this story now contend.
Given the criterion of Passover as to “why” Jesus and his disciples were gathered together to share the event, Passover with its emblems of unleavened bread and wine, its historical and religious significance, all of which Jesus and his disciples were there to observe (a matter of no small significance which both Leonardo and Mr. Brown seem to have overlooked), the single cup described by the writers of the NT (who unlike Leonardo were actually there) all of those descriptive elements leave only one conclusion possible as to what Leonardo was and was not intending to paint.
I don't understand.
Why do you say that 'Leonardo and Mr. Brown' overlooked the fact that this meal was part of Passover?