1. The need for a stallion
We could very well admit that on an exchange platform we can exchange everything with ratios. The number would serve as a standard because, according to Einstein’s “The world as you see it” (Mein Weltbild), the resultant ratio would determine a value. The example would be that a chicken is exchanged for 40 eggs. However, it must be assumed that this would imply that all platforms, for balances released, are linked with an exchange ratio. Otherwise, this balance which must be considered by the holder, would not be like “as good as money”. He will refuse to make the transaction if, when it is contemplated, he leaves him a “worthless” balance. Above all, the question of the fate of balances would be asked if the ratios can not lead to compensation. To avoid this wall it would be necessary that a platform, such as that of AMAZON, becomes a universal object. You can find everything and you can buy everything and exchange. But then we will face the obstacle of the domination of the market by a single actor which we know by historical examples to what mistakes it can lead.
The role of intermediation of the currency which frees its holder of compulsory choices since he can freely move from one offer to another would be flouted. It would be subject to the defined offer made by the platform.
This hypothesis also comes up for the moment with rules specific to certain types of exchanges, such as real estate transactions that must follow specific procedures (registration) and go through sworn agents (lawyers or notaries). It also comes up against the various monetary sovereignties that want certain transactions to be carried out only in the currency of residence of one or both parties. In addition, even assuming a formula to round balances, the only ratio does not account for the time that the value will vary according to different cycles for the goods or animals traded. The hen will last longer than the eggs. In fact, implicitly the balance will be accepted only if it is assigned an exchange value which, in the absence of a monetary standard, will be the capacity of the platform to establish that the balance will be exchangeable in the future against other numbers valuing the goods put to the exchange. More fundamentally, the exchange cycles being different according to the actors a balance is necessary. Thus, for example, the car manufacturer sells the cars he produces each day, while the buyer only buys them in a discontinuous manner and spread over time. It therefore requires the latter a valuable storage capacity to make this kind of purchase. In the same way, the “distribution” necessary for today’s social life implies that a reserve be made for the benefit of the retired or for the benefit of the children for their education. In the case of rights to be satisfied over time, it is necessary to take the value from some to attribute it to others or to accept the savings of some, a standard that can be used to determine the associated powers. Otherwise, you would never agree to contribute on your salary or even that your employer contributes for you, to serve you a retirement of which you would not know what kind of standard of living it will allow you when the time comes. The standard is therefore necessary, not only for the purposes of visibility of distribution rights, but also so that they can be modulated according to the needs. To ensure what is conventionally referred to as the reserve function of money, a standard must be associated with it to account for the “time” dimension.

2. The necessary characteristics of a standard a) Stability
Obviously, the cycles to which our production is subjected, such as our consumption and our way of life, are of variable duration, like the life of the goods we consume. For this reason, and to provide the transparency necessary for the confidence an economy needs, the standard must be stable. In this respect, the volatility of the value of the standard has a distributive effect because as soon as it has been associated for its measurement with a good, it gives a value. Any debt is also a debt for its counterpart. Changing the value of the standard has the effect of modifying the term rights of each party, debtor and creditor. In times of inflation, the holder of fixed incomes suffers it. On the other hand, the debtor profits from an increased distribution.
A high intrinsic volatility of the standard would be intolerable since since it becomes alive by its association with a support, such a phenomenon without law, becomes redistributive. This redistribution essential to our societal functioning without logic and especially without democratic control is to be banned. It destroys the functioning of the market economy since it will act on the price of trade without a direct look at the service or good exchanged, its usefulness, its scarcity or its cost. The retiree becomes richer or poorer without any behavioral logic and without any reason likely to win its adhesion or that of the other economic agents who would be deprived of values. It is also the problem of the monetary wars where each one is lowering its currency to favor its domestic production to the detriment of its competitors. Mechanisms that set prices and allocate resources no longer work. Markets are unduly disturbed.
b) Universality 
First of all, what is universality here? It is not only a physical reality of the stallion but also as always in monetary matter of an easy recognition thus shareable by the potential users 
The stallion has always been historically of physical nature because having this characteristic, it transcends the human being. It is the speed of light, it is the molecule of gold or silver. The human being can not violate the characteristics and they serve as benchmarks. It is neutral in relation to the actors and therefore it is the prices which vary and not the standard. 
The molecule responds to the need for universality, which is also necessary for a stallion because, no matter who observes it, it is unique.
Being a molecule, very tangible at first noticeable (we know how to recognize gold and our Greek ancestors already supposed existence), it is exchangeable as such by its definition and weight, the same for each observer or actor. I used to say that the first monetary union was achieved by the issue in Lydia of gold coins (5th century AC).
With respect to a cryptogram, if its universality can be assured, it may lack transparency for some. This is probably only a question of generations. In the absence of transparency, phenomena of rejection of one by the others could occur. There is an educational subject despite the wonder of the practicality that will push him to universality by the attraction it will generate and the “authority” that universality confers as the authority that it confers and which brings the mystic closer. Here again we see the relationship of mathematics with the social and its indecisive boundaries. It involves studies and flexibility in the context of societies 
c) Practicality and inviolability
Obviously, because of its availability of rarity, and its low corrosion gold is both a standard and an ideal support. It may be even better as a standard in terms of its transport and its accounting, that is to say its storage. 
The best is the cryptogram. Of course, the cryptogram, has no weight and is digital. However, it also needs to be as inviolable as the definition of a molecule. Which cryptogram will have this characteristic and how to insure it. Is this the case of the current digital currencies which are at the same time support and standard? Probably not as such but I can not answer the question, especially in the presence of major specialists in encryption, digital currencies and their operability.
It is this concern that has probably led bitcoin designers and others to consider the blockchain. 
But the problem is that a cryptogram does not have any value. But the reserve function implies a value to the monetary support that is given to it by what our books call “stamping” the stamping the conjugation of a support and the calibration.
A number is a ranking mode but does not confer value because unlike a metal, such as gold or silver, it has no intrinsic value. A cryptogram has no more value. Yes, but unique and rare it can however take a more or less value depending on whether it is more or less inviolable because then it becomes usable as is a lock to protect his property, his reserve. It is rare because it has to be developed and has the cost of this development (computer power and electricity involved in the implementation of the latter). What’s more, like Uncle Scrooge’s gold coins on his gold pile (Disney), he becomes susceptible to buildup.
But to come to life, it must be associated with either a debt issued that would be exchangeable or issued independently. In both cases, even if the legal and tax statuses are different, we are in the presence of monetary units. A number of units and not the number itself is associated with a value.
We can clearly see here the mystical character that can be attributed to the monetary unit when one has the power to free it from its abstraction by associating it with a claim, this right of exchange, and that from then on takes a value. This is called the seigniorage privilege that everyone would like to have, that of creating nothing of value, transmuting lead into gold. Because of the fear of the future, the reasonable human being, to protect himself, likes to accumulate value. We have already addressed this issue of the value of a cryptogram that inviolable, may become rare and respond to the laws of demand and supply markets but affect the allocation of resources of our economies.

3. The blockchain a possible contribution to the security of stallion tracking and inviolability – the opposite of anonymity? 
Let me first give you my vision as a basic accountant on what the blockchain is about in the world of human exchanges.
The blockchain is a device intended to prove the integrity of the recording of the image of an exchange between beings or machines having autonomy. It therefore implies an object and autonomous beings. Since it will be passed between at least two beings (human or societal) the exchange itself becomes common but also autonomous because it can not be modified in its characteristics (object – price) without the agreement of the other or rather, if it is changed, it is another exchange. It will be an image, a contract, a right an object like a bitcoin. In our universe everything is unique. We can start with the human being. MX is unique whether or not it is normal. If you see two, you have a brain or vision disorder or one is a transvestite. The image by different processes can be double or even represented a similar reality but the reality is unique, it is its image that can be multiplied. Obviously, the exchange and trust between humans implies that they see the same image and make sure to chase duplicates and transvestites. To do this, for example, in the 15th century a Dominican, employed in a bank, describes a process called “the double part” which transcribes (in a work called “The suma”) the idea that if I priest 100 guilders to Monsieur X this one owes me the same sum. So, will he write in his account book that he withdrew 100 Florins from his chest since he gave them to Mr. X and now he has a loan against the same MX who tells them. He records a claim of 100 Fl at the rate of his book and a decrease of FL 100 of his cash. Of course, MX’s books should be reciprocal, the fund increasing, and the debt for the same FL 100. This recording later appeared useful for demonstrating the proof of the transaction. Thus, the accounting books have become mandatory by law for merchants (Commercial Code Article L 12312). But how does one make the accounting book become proof? The legislator first provides that the book is quoted and initialed in the commercial court with a date for this operation and that it is linked so that it can not tear or add a numbered sheet made of an unalterable paper (as would the paper of a bank note). Then,
Today the device still exists in a renewed digital form. This is the FEC Accounting File established by the Decree of 29 July 2013 which transposes a European text.
The blockchain is nothing more than a device intended to ensure the uniqueness of the recordings and their chronological classification, as counting ensures. Obviously, no more paper, no visible erasures, no more chemistry to erase the ink after an error …. The security device is not that the sums exchanged between praetor and borrower are reciprocal even if they are still reciprocal by definition of the contractual right. What the blockchain does is that the recording being decentralized, copies are made in a continuous manner and that if one unilaterally “corrects” one of the copies, the copies of the book will no longer conform. The chronology is also a necessary axiom which is not a novelty but which is ensured by the one-way “hash” of the blocks that allows the computer which conjugates to the uniqueness of the facts in ensures the relative inviolability. The fraud that would change a writing would be seen because it would not be the same writing that one would seek to cancel or partially neutralize. It will therefore be visible and seen.
It should be noted that a single dissociation would be sufficient to ensure the integrity of the transaction or rather its supervision if the copy made was stored in an independent hierarchical authority that would have supervisory power (vision) of the operator, especially if was not reciprocal. The blockchain differs from this scheme since the system is collaborative both recording and monitoring. We understand immediately that there is a question that is who has the arbitration keys in case of anomaly, first analysis, then solution.
Is one scheme superior to the other? It is a question of first of cost of treatment and in particular of the cost of the energy. It is also a question of social organization. Probably, the object and the use are the important factors of the answer. For example, for public purposes such as the preservation of documents that are supposedly public as a notarial act of property (which will be stored in the mortgage register) the system has great virtues because of searchable, it becomes shared between a defined number operators who are by equal status, Notaries in France, lawyers in many other countries. Volumes are small. Different, is the monetary usage.

4. L’Usage Monétaire: Les caractéristiques nécessaires.
Il s’agit comme on le sait d’un sujet différent même si par exemple le bitcoin utilise la technique de la blockchain pour garantir l’unicité du support donc prouver l’intégrité des transactions rapportées.
Pour répondre aux besoins monétaires il faut non seulement un étalon, mais aussi que la quantité de monnaie disponible dès lors émise, puisse être ajustée aux besoins afin que sa valeur soit assez stable mais suffisamment flexible pour servir de régulation supérieure en cas de besoin. Il faut à la fois assez de monnaie liquide et d’instruments financiers pour satisfaire aux besoins des agents économiques et de leurs échanges. Il s’agit d’une vaste question car tout instrument de dette est une monnaie virtuelle de liquidité différente et de vitesse de rotation variable comme le sont les besoins d’échange, cela selon le moment (par exemple pour l’agriculteur selon les saisons). C’est une raison de plus pour que l’étalon soit stable et que la quantité de support puisse être ajustée. C’est une des explications que dans un contexte non inflationniste du fait d’un ralentissement des échanges et donc de perte de valeur, avec un étalon – le dollar devenu – autonome il a fallu compenser la perte de valeur des portefeuilles d’instruments par de très lourdes injections monétaires, les QE. On a depuis longtemps (Bodin 15ème siècle) démontré l’existence d’un effet à la quantité monétaire.
Ce qui est en jeu, c’est l’édifice social et le système politique. Une inflation par exemple, joue comme un impôt. L’impôt selon son usage va avoir des effets différents comme l’émission monétaire. Tout est en jeu, le système de prix, comme par effet induit, le système de répartition et le pouvoir.
Pour cette raison, un système qui aurait pour vertu d’être autonome ne serait pas viable. C’est par exemple démontré par la situation des pays frappés par la malédiction de disposer de matières premières valorisées qui en fait sont sur-financés gratuitement (sans travail).
Une monnaie virtuelle est tout à fait envisageable et même probablement un progrès déjà existant car notre système financier, n’est déjà plus que virtuel.
Il ne peut pas survivre sans régulation de la valeur des supports. Mais aussi, les vitesses de rotation des dispositifs d’échange et de sécurité d’une monnaie cryptographique sont en jeu dans la mesure où certains sont plus rapides que d’autres. A qui la confier le soin d’assurer l’universalité nécessaire du support tout en probablement prévoyant différents dispositifs d’échange pour assurer différentes vitesses, comme comment déterminer les quantités adéquates est un sujet différent de l’étalon que nous n’avons plus autrement que par le dollar (85% des échanges interbancaires et des quantités de devises traitées). En soit, il ne m’apparait pas que l’anonymat soit intrinsèque aux systèmes collaboratifs autrement que par convention. On sait retrouver les adresses IP, comme par recoupement des observations et suivi des blocs retrouver les identités de celles qui seraient cachées, en soit déjà une source d’identification quand d’autres sont visibles. Par ailleurs, dans le contexte actuel l’attente du public pour des raisons de sécurité l’anonymat comme la protection des données individuelles doivent avoir des limites qui sont dans l’usage fait d’instruments à pouvoir libératoire (drogues, prostitutions, spéculations financières répréhensibles etc). La lutte contre le blanchiment implique cette limite. A qui confier ce pouvoir comme comment mettre fin à l’anonymat dans les conditions judiciaires de garantie des droits des individus, reste à établir. En plus du pouvoir judiciaire situé en haut des systèmes constitutionnels démocratiques, des administrations civiles existent déjà avec ces pouvoirs. Reste la difficulté de leur juridiction géographique sur un monde digital dont les frontières n’existent pas encore vraiment. Il est probable que des traités soient nécessaires comme lorsque les doits maritimes et ferroviaires ont été mises en place pour la prospérité de l’humanité grâce aux échanges rendus possibles. Le sens des choses rend la monnaie digitale obligatoire mais ses dispositifstechniques possibles nombreux sans même prendre en compte les progrès incessants des outils. Où et à quel moment s’arrêter sur une solution universaliste m’apparait aujourd’hui plus qu’hier, grâce à votre journée et aux brillants exposés qui s’y sont succédés une question qui reste ouverte. Celles qui permettraient la flexibilité tant de l’étalon que des supports et des systèmes d’échange forment surement la voie à suivre.
It was an honor for me to come and talk to you about the constraints and hopes I saw. 
The digital currencies as the intellectual exchanges authorized by this day of which I thank Ricardo Perez Marco and his team of the Labex of Financial Modeling to have allowed the success contribute to the progress of the subject. I have also seen the entrepreneurial force that it generates and which is associated with it and which contributes to this progress in an essential way by the relation which it creates with the potential user. I thank them for inviting me