I have heard both versions given in Cecil’s column but the one I believe to be most likely true is this (if she ever really said “Let them eat cake” at all):
Marie Antoinette was, obviously a princess and then queen, and never lifted a finger to do anything for herself in her life. She was also completely out of touch with the reality of the starving population. This among other things led to her unfortunate demise. I read (who knows where) that upon being told the peasants had no bread she replied with her famous line. NOT out of derision or mocking but rather because she had no concept whatsoever of people starving. She herself must have been presented with mounds of food each day. So the peasants don’t have bread; they should eat cake or puff pastry or croissants instead, just like she did when the overloaded banquet table was temporarily out of her favorite snack.
Kind of like if you saw a homeless person who said he is starving and has no money to buy a hamburger and you said, with all sincerity and naïveté, “Oh, then get some chicken fingers instead.” Point being that he, like the peasants, has no money for any food, not just hamburgers (or bread). But you (and Marie), in your ivory towers, can’t conceive of such a thing.
On the other hand, given that Rousseau wrote about “a great princesss” 30 years earlier, she probably never said anything of the sort.
They way I’ve heard the story go on Marie Antoinette’s supposed remark “Let them eat cake” is that she probably didn’t say it. At least not in that direct a fashion. If she had said it, though, it almost certainly had nothing to do with brioche (sort of).
Most of the baking ovens of the day were single compartment affairs, which meant that the fire was lit in the same chamber where the baking took place. Once the fire burned down to coals, then the bread dough was put in to bake right next to the coals. But inevitably some of the coals migrated over to the baking part of the oven. The easiest way to sop them up was with a bit of the raw dough, which, once it had baked a bit, could simply be removed and discarded. There was then a clean surface to bake the bread on.
So if sweet Marie had acknowledged the existence of the peasantry for something beyond taxation, she was still not going to be beloved by the people of France for it.
Cecil concentrated too much on the “brioche” part of the second letter and not enough on the “let them eat bread-baking scraps” part, which was the real gist of it. So what if the name was wrong, the concept could be right, and bears further investigation IMO.
Yeah, I think dear old Cecil missed the boat on the second letter, too. He says “N” is wrong and brioche is fancy pastry, not discarded lining scraps. But “N” says it was previously known as the scraps, then acquired a new meaning for fancy pastry. Did Cecil even read that letter?
Remembering what I do from my history class, Marie Antoinette was married off in an effort to help Austria. She was Austrian. The riegning queen of France at the time hated her, and she was married to a rather repulsive glutton.
Knowing full well that she would probably be executed during any riot or revolution that ensued, she had every right to say, “let them eat cake!”
To further a point made in AUE’s FAQ (to which samclem linked, above) regarding the alleged longevity of this expression, I’ll point out that a dictionary of quotations notes that,
In fact, here’s the know-all’s letter regarding Peckham’s alleged use of the phrase,
Who knows, it might be worthwhile tracking down what Mr. Ward was referring to.
I think more importantly, however, that entry also points to a variant that is sometimes linked to Joseph Foullon de Doué, Comptroller of Finances at the time of the Revolution. Notably, that Foullon was alleged to have responded in this fashion, sometime in the summer of 1789, to the news that bread was scarce made it to American shores within 2-½ months of his execution,
In the end, though, we have (at least) two extant tellings in French involving female members of a royal family.
As has been pointed out, Rousseau’s version (ca. 1770) featured an great unnamed princess of the past,
And Louis XVIII, who was at one point Marie Antoinette’s brother-in-law, recounted in 1823 an incident that occurred during his departure from France in 1791. During his flight, he noted that he had cause to remember the family anecdote involving Louis XIV’s wife,
So, you see – cake or no cake – as Alphonse Karr himself would say, “plus ça change, plus c’est la même chose.”
– Tammi Terrell
 In fact, historian Jonathan Dewald maintains that 19th-century French historian Hippolyte Taine “described the seventy-four-year-old Foullon, for instance, being marched to Paris ‘a bundle of hay on his head, a necklace of thistles around his neck, his mouth stuffed with hay.’”
I’d be curious to see a contemporaneous account in French. (For what it’s worth, “hay” translates in French as “paille,” which has some obvious similarities to “pain.”)