NOTRE AMÉ ET FÉAL, nous avons besoin du concours de nos fidèles sujets pour nous aider à surmonter toutes les difficultés où nous nous trouvons, relativement à l’état de nos finances, et pour établir, suivant nos vœux, un ordre constant et invariable dans toutes les parties du gouvernement qui intéressent le bonheur de nos sujets et la prospérité de notre royaume. Ces grands motifs nous ont déterminé à convoquer l’assemblée des Etats de toutes les provinces de notre obéissance, tant pour nous conseiller et nous assister dans toutes les choses qui nous seront mises sous les yeux, que pour faire connaître les souhaits et les doléances de nos peuples : de manière que, par une mutuelle confiance et par un amour réciproque entre le souverain et ses sujets, il soit apporté le plus promptement possible un remède efficace aux maux de l’Etat, et que les abus de tout genre soient réformés et prévenus par de bons et solides moyens qui assurent la félicité publique, et qui nous rendent à nous, particulièrement, le calme et la tranquillité dont nous sommes privés depuis si longtemps.
OUR BELOVED AND LOYAL, we need the participation of our faithful subjects to help us overcome all the difficulties we are facing with respect to the state of our finances and to establish, according to our [everyone] wishes, lasting and steady order in every aspect of government that concern happiness and prosperity in our realm. These important motives have led us to convene a meeting of the Estates of each province under our rule, both to advise and assist us in every area that will be brought before our eyes, as well as to let us know the wishes and grievances of our people, so that, through mutual trust and deep affection [amour] between the king and his subjects, a remedy may be found, as promptly as possible, to the ills of the land and reforms may be effected that will prevent abuses of all kinds using good and solid means that will ensure the satisfaction [félicité] of the public and give us [the king] the calm and tranquillity we have been denied for such a long time.
(24 January 1789)
The above translation is mine. It is not an official translation. Louis XVI wrote his Notice of Meeting on 24 January 1789, which seems a late date. However, Étienne-Charles de Loménie de Brienne, the king’s minister of finance in 1788, had announced this meeting of the Estates-General on 8 August 1788 and set the opening of the Estates-General for 5 May 1789.
In the last quarter of the 18th century, France was on the brink of bankrupty. It had incurred debts that could not be paid unless taxes were levied from the First and Second Estates, the clergy and the nobility. The king appointed various finance ministers, all of whom were serious individuals and some extremely competent. Each came to the conclusion that France had to levy taxes from sources other than the Third Estate.
France may have been an absolute monarchy, but once absolutism reached Louis XVI, it was diluted. The king and his finance ministers could not circumvent the Parlements.
The beginning of the proposed radical changes began with the Protests of the Parlement of Paris addressed to Louis XVI in March 1776, in which the Second Estate, the nobility, resisted the beginning of certain reforms that would remove their privileges, notably their exemption from taxes. The objections made to the Parlement of Paris were in reaction to the essay, Réflexions sur la formation et la distribution des richesses(‘Reflections on the Formation and Distribution of Wealth’) by Anne-Robert-Jacques Turgot.
Finally, as we have seen, the sale of offices had turned a significant segment of the population of France into a bourgeoisie:petite, moyenne (middle) and haute bourgeoisie. Many bourgeois were rich and some worked at court. I have mentioned that Jean-Baptiste Colbert, a bourgeois, was Louis XIV’s Minister of Finances, from 1661 to 1683. So l’abbé Sieyès’ Third Estate differed from the Third Estate that was convened in the Estates-General of 1614, 175 years before 1789. France had changed.
In short, Louis XVI should not have been compelled to convene the three estates. But he and his ministers of finance were ruled, and overruled, by the Parlement of Paris.
[The] Parlement of Paris, though no more in fact than a small, selfish, proud and venal oligarchy, regarded itself, and was regarded by public opinion, as the guardian of the constitutional liberties of France. [I underlined constitutional.] 
When delegates arrived at Versailles, there was confusion. Would they sit by ordre (estates), or would estates be mixed? Would they vote by ordre (estate), or by head? Delegates got so bogged down in such matters as representation that Louis would no longer hear them. On 20 June 1789, the king had the doors to the rooms where delegates met locked down. The deputies were not focussing on replenishing France’s empty coffers, the matter that so preoccupied Louis XVI.
We are familiar with the rest. Finding that the doors to Versailles had been locked, delegates met in a neighbouring Tennis Court, where 576 out of 577 delegates swore:
“not to separate, and to reassemble wherever circumstances require, until the constitution of the kingdom is established.”
(See The Tennis Court Oath, wiki2.org.)
By 17 June 1789, delegates had started calling themselves the National Assembly, on a proposal of l’abbé Sieyès. In fact, on 13-14 June, nine priests had joined the Assembly. Therefore, the self-proclaimed National Assembly lasted from 13 June to 9 July 1789, but was replaced by another Assembly. Henceforth, underlying the problematic of the French Revolution was the co-existence of a monarchy and an assembly, which the creation of a Kingdom of France confirms.
As noted above, I suspect that delegate Martin-Dauch voted differently than other delegates because he looked upon the monarchy as the government. The Estates-General had not been convened since 1614, but it existed. So did the Assembly of Notables, who had come to Versailles in 1787. Finally, France had its Parlements. Not only was the assembly self-proclaimed but its relationship with the king was confrontational which may have caused the king to invalidate decisions made by the Assembly that he would recognize a few days later. I have borrowed the words “confrontation” and “recognition” from wiki2’s entry on the National Assembly.
For instance, on 23 June 1789, the king invalidated decisions made by the Assembly, which led the comte de Mirabeau to shout, defiantly:
“A military force surrounds the assembly! Where are the enemies of the nation? Is Catiline at our gates? I demand, investing yourselves with your dignity, with your legislative power, you inclose yourselves within the religion of your oath. It does not permit you to separate till you have formed a constitution.” (See National Assembly, wiki2.org.)
Therefore, on 27 June 1789, “Louis XVI reverses course, instructs the nobility and clergy to meet with the other estates, and recognizes the new Assembly. At the same time, he orders reliable military units, largely composed of Swiss and German mercenaries, to Paris.” (See Timeline of the French Revolution, Wiki2.org.)
In the meantime, on 25 June 1789, 48 nobles had joined the Assembly. The group’s leader was Louis Philippe II, Duke of Orléans, or Philippe Égalité, Louis XVI’s first cousin who would vote in favour of the King’s execution.
However, Republicans, in the unicameral Assembly, demanded the removal of the king. A petition was signed by 6,000 persons and 50 persons were killed when Lafayette quelled the demonstration. This event is remembered as the Champ de Mars Massacre. (See 17 July, Timeline of the French Revolution, wiki2.org.) Moreover, on 16 May 1791, “on a proposal of Robespierre, the Assembly [had voted] to forbid members of the current Assembly to become candidates for the next Assembly,” (See 16 May, Timeline of the French Revolution, wiki2.org.) which suggests that Robespierre opposed supporters of a reformed French Monarchy.
Louis XVI was forced to sign the Constitution of 1791, but for one year the National Legislative Assembly ran concurrently with the Kingdom of France. Louis XVI found fault with the new Constitution. For, instance, it was unicameral (one chamber), rather than bicameral, thus differing from Britain’s Constitutional Monarchy, which had been the model. The king also bemoaned the removal of his right to veto. How would he protect émigrés? Madame Adélaïde and Madame Victoire, the king’s aunts had left for Rome. During the French Revolution, Republicans forever asked that those who had left be forced to return home. Under the Constitution of 1791, all the king could do was choose his ministers, which was viewed as a separation of powers. However, on 13-14 September 1791, the king accepted the new Constitution formerly.
But sovereignty effectively resided in the legislative branch, to consist of a single house, the Legislative Assembly, elected by a system of indirect voting. (‘The people or the nation can have only one voice, that of the national legislature,’ wrote Sieyès. ‘The people can speak and act only through its representatives.’) 
“Dismayed at what he deemed the ill-considered radicalism of such decisions, Jean-Joseph Mounier, a leading patriot deputy in the summer of 1789 and author of the Tennis Court Oath, resigned from the Assembly in October.”
A similar view was expressed in the 20th century by François Furet (27 March 1927 – 12/13 July 1997, go to restructuring France) of the French Academy. (Also see François Furet, wiki2.org.)
They [persons who drafted the new constitution] effectively transferred political power from the monarchy and the privileged estates to the general body of propertied citizens. 
Under this system about two-thirds of adult males had the right to vote for electors and to choose certain local officials directly. Although it favoured wealthier citizens, the system was vastly more democratic than Britain’s. 
Louis XVI convened the Estates-General because he wanted the people of France to allow its government to effect tax reforms so a debt would be eliminated. But the comte de Mirabeau was not part of the people whose help the king needed? He was a self-agrandizing agitator.
Regarding the flight to Varennes, it has been suggested
[t]hat royalists should have seen in this escape the means [of] placing the King in safety, and of crushing the Revolution at the same time, was but natural. 
The Third Estate needed to be something. Privilege, tax exemption particularly, had to be revised. As well, the time had come to declare the rights of citizens. But regicide and the Terreur? Radicals took over.
____________________ Alfred Cobban (1957). A History of France. 1. p. 63. see also Cobban, “The Parlements of France in the eighteenth century.” History (1950) 35#123 pp 64-80. (Quoted under Parlement, wiki2.org.)
L’abbé Sieyès presented a portrait of the Third Estate that described its ampleur or magnitude, especially the bourgeoisie’s. L’abbé Sieyès’ pamphlet was not a call to arms, but it stated that the Third Estate, 98% of the population, should be “something.” It was “everything,” but it had been “nothing” “in the political order.”
What is the Third Estate? Everything.
What has it been until now in the political order? Nothing.
What does it want to be? Something.
By becoming a priest, l’abbé Sieyès had elevated himself to the noblesse de robe, nobles of the robe. It comprised persons “whose rank came from holding certain judicial or administrative posts.” (See Nobles of the robe.) As members of the clergy, priests could sit among delegates of the First Estate, the clergy. However, l’abbé (abbott) Sieyès was not an aristocrat who had chosen the priesthood, but a bourgeois who had become a priest. He knew, in other words, that the old aristocracy resented the new aristocracy. (See the History of Nobility, acquired nobility.)
L’ancienne noblesse ne peut pas souffrir les nouveaux nobles; elle ne leur permet de siéger avec elle que lorsqu’ils peuvent prouver, comme l’on dit, quatre générations et cent ans. Ainsi, elle les repousse dans l’ordre du Tiers état, auquel évidemment ils n’appartiennent plus. (p. 10)
The old aristocracy detests new nobles; it allows nobles to sit as such only when they can prove, as the phrase goes, “four generations and a hundred years.” Thus it relegates the other nobles to the order of the Third Estate to which, obviously, they no longer belong. (p. 3)
Born a bourgeois, l’abbé Sieyès chose to represent the Tiers-État, the Third Estate. It was everything. And it was growing. The sale of offices could lead the buyer, a peasant, to the bourgeoisie, which had ranks: petite, moyenne [middle] et grande). Blaise Pascal‘s (19 June 1623 – 19 August 1662) father was supervisor of taxes in Rouen, an office one could buy and transformed its owner into a bourgeois. Molière‘s father, Jean Poquelin, had purchased his post, “valet de chambre ordinaire et tapissier du Roi” (“valet of the King’s chamber and keeper of carpets and upholstery”), under Louis XIII.
Some bourgeois were very rich and very powerful. Jean-Baptiste Colbert (29 August 1619 – 6 September 1683), served as minister of finance to Louis XIV, from 1665 until 1683. Finally, Louis XIV could not trust aristocrats. He remembered La Fronde (1648-1652), when aristocrats opposed absolutism. They had lost their role. Louis XIV’s advisors were bourgeois who constituted the Conseil du Roi, called the Conseil d’en haut, because they met “en haut,” upstairs. Peasants had not escaped feudalism altogether, but feudalism was waning.
“Consequently, the Third Estate represented the great majority of the people, and its deputies’ transformation of themselves into a National Assembly in June 1789 marked the beginning of the French Revolution.”
Therefore, it was in Sieyès and the Third Estate’s best interest to ask that “votes be taken by heads and not by orders.” An “ordre” was an Estate.
L’ abbé Sieyès stated that the people wanted genuine representatives in the Estates-General, equal representation to the other two orders taken together, and votes taken by heads and not by orders. These ideas came to have an immense influence on the course of the French Revolution.
Among the many causes of the French Revolution, the editors of the Encyclopædia Britannica write that “the bourgeoisie resented its exclusion from political power and positions of honour,” which would be the first cause of the French Revolution and which encapsulates Sieyès’ What is the Third Estate. The Third Estate was “everything,” yet “nothing.” I believe many scholars would also consider the bourgeoisie’s “exclusion from political power” a cause of the French Revolution.
In a letter dated November 26th, 1831, he [Tocqueville] criticizes France’s dealings with its North American colony during the 18th century, referring to the ‘abandonment’ of loyal subjects of the French Empire. Then he adds that it was ‘one of the greatest ignominies of Louis XV’s shameful reign.’
A 13th-century French representation of the tripartite social order of the middle ages– Oratores: “those who pray”, Bellatores: “those who fight”, and Laboratores: “those who work”. (Caption and photo credit: Wikipedia)
This lovely historiated initial, shows France’s three classes. Not only did the third estate, le Tiers État, work, but it also paid the taxes that supported the clergy, the first estate, and the nobility, the second estate. During the last quarter of the 18th-century, France was near bankrupcy, mostly because of its recent financial contribution to North-American colonists seeking independence from Britain.
France could have helped the North-American colonists, but absolutism and Louis XV’s profligacy had strained and humiliated France. In 1763, it lost New France.