Serious reasons almost retarded Mlle de Montpensier’s marriage.  The young princess arrives in Spain suffering from a violent engorgement of her neck glands, which is believed to have been caused by the fatigue of a long voyage, undertaken in the most rigorous season.

This glandular engorgement is only the warning symptom of an erysipelas (infectious illness, characterised by an inflammation of the skin, particularly the derm, and generally localised on the face) which soon declares itself.

The King, who first of all thinks that she has smallpox, is very alarmed.  Saint-Simon reassures him by revealing that the Princess has already had this disease, as well as the measles.

This revelation throws the Spanish sovereign into great agitation.  “Then, if it isn’t smallpox, it could be… ”  The King and the Queen no longer hesitate in confiding in the noble Duke.  To dissipate their growing anxiety, a clear explanation becomes necessary.

The King of Spain has heard about the licentious morality of the Palais-Royal.  The Regent’s indiscretions are known to him.  Could his daughter have inherited some blood vice, which is manifesting itself by these unusual rashes on her neck?  Saint-Simon understands that he will get nowhere by trying to avoid the truth.

Without hiding from the King that the Duke d’Orleans has not always had an exemplary conduct, he assures him, very firmly, “that it had always been without any bad consequences”, that “his health had always been good and above suspicion;  that he had never ceased, even for a day, to appear in his ordinary state”, that, having lived constantly “in such great intimity with him that it would have been absolutely impossible that the slightest unfortunate consequence of his sexual pleasures could have escaped him, he could swear to Their Majesties that never had he noticed any;  that Madame, the Duchess d’Orleans had always enjoyed the most constant and the most perfect health, and had fulfilled each day in the King’s apartments, in her own apartments and everywhere, the public duties demanded of her rank, and that none of all of her children had ever given cause for the slightest suspicion of that nature, concerning his or her health”.

This warm plea does not appear to dissipate the apprehensions of Their Catholic Majesties.  The glands not shrinking, the First Doctor of the Spanish court receives the order to write directly to Chirac, the Regent’s doctor, to find out the whole truth on the genital health of his august client.

The King and the Queen, convinced that the illness is not contagious, decide to visit their daughter-in-law.  “The Queen did not hesitate to give her broths and whatever else that she had to take.”  The royal couple goes several times a day to the patient’s bedroom.

As for Saint-Simon, he prudently stays away.  He says that he is being careful not to disobey the custom which, in Spain, does not allow a man to see a woman in bed, for whatever motive.

It takes the formal order of the King to vanquish his resistance.  Saint-Simon obeys and, whether he likes it or not, has to examine the Princess with the greatest care, looking  inside her extremely inflamed throat with a magnifying glass, like a vulgar consulting doctor.

Is it to his long friendship with the famous surgeon Mareschal that Saint-Simon owes his penetrating clinical eye?  Whatever the reason, he is the first to recognize the close relationship between glandular engorgement and erysipelas, which is attested by a letter which he writes to the Duke d’Orleans.

“Everything leads to believe that these glands are only congested by the neighbouring erysipelas, and that they will recover at the same time as the cause which made them swell.”  This is proof of a singular prescience.  At this time, no medical treaty mentions this symptom of erysipelas.

It is commonly admitted that it is Chomel, who lived under Louis-Philippe, who was the first to see glandular engorgement as a symptom of erysipelas.  Saint-Simon preceded Chomel by almost a century.

His prognosis is fully verified.  In a few days, the swelling disappears, the erysipelas evolves normally, and the Princess of the Asturies recovers.

Fifth and last part tomorrow.