Marie Antoinette never said “let them eat cake” but she might have said “let them follow the rules” because there were a lot of rules to follow at Versailles. For the king and queen as well as the courtiers.

Seating arrangements: whether or not you were allowed to sit in the presence of the king and queen was determined by your rank. The king and queen sat in armchairs along with any visiting monarchs, the brothers or children of the king were allowed chairs with no arms, other very high ranked people were allowed stools. Everyone else had to stand.

Around the Palace:

• Courtiers were not allowed to knock at doors. Rather, they used their little fingers to “scratch” at the door to be let in, with some people growing out their pinkie nail for that purpose.
• Courtiers were also not allowed to open doors. An usher had to open the door for them.
• Men and women weren’t allowed to hold hands or link their arms together (this probably would have been impossible anyway, due to very large skirt size at the time), so they had to stroll through the gardens with their arms out at 90 degree angles (like you do in your driver’s test to prove you know the arm signals for left, right, and stop) and the lady’s arm resting on top of the gentleman’s.

A very public life: Louis XVI and Marie Antoinette, as king and queen were subjected to close public scrutiny at all times. Every morning, Marie Antoinette (and the king in his own room) had to go through a ceremony called a levee in which she was awoken and washed and dressed by her courtiers in front of anyone with a high enough rank to be allowed to enter. The couple also had to eat dinner publicly during the Grand Couvert. Anyone of rank could crowd into the room to gawk at the king and queen, as long as they were dressed properly, ie men had to wear swords (luckily you could rent one if you forgot yours!). Marie Antoinette hated this ritual so much that she would pick at her food and have her real dinner sent to her rooms later.

Part of the reason etiquette was so important at Versailles was that the French kings brought all of their nobles to court to keep an eye on them and prevent them from developing their own power centers in their home regions and becoming a threat to the monarchy. The king also used the elaborate and constantly changing etiquette to keep the courtiers in check and on their toes. If you followed all the rules and did everything splendidly, the king might take notice of you and allow you more and more access to him. With that access came influence and power. If you did something to disgrace yourself, the king wouldn’t even “see” you if he passed you, thus you ceased to exist as far as any political influence went.