With all his politeness, which was in no way put on, M. de Coislin could, when he pleased, show a great deal of firmness, and a resolution to maintain his proper dignity worthy of much praise.  At Nancy, on this same occasion, the Duc de Crequi, not finding apartments provided for him to his taste on arriving in town, went, in his brutal manner, and seized upon those allotted to the Duc de Coislin.  The Duke, arriving a moment after, found his servants turned into the street, and soon learned who had sent them there.  M. de Crequi had precedence of him in rank; he said not a word, therefore, but went to the apartments provided for the Marechal de Crequi (brother of the other), served him exactly as he himself had just been served, and took up his quarters there.  The Marechal de Crequi arrived in his turn, learned what had occurred, and immediately seized upon the apartments of Cavoye, in order to teach him how to provide quarters in future so as to avoid all disputes.

On another occasion, M. de Coislin went to the Sorbonne to listen to a thesis sustained by the second son of M. de Bouillon.  When persons of distinction gave these discourses, it was customary for the Princes of the blood, and for many of the Court, to go and hear them.  M. de Coislin was at that time almost last in order of precedence among the Dukes.  When he took his seat, therefore, knowing that a number of them would probably arrive, he left several rows of vacant places in front of him, and sat himself down.  Immediately afterwards, Novion, Chief President of the Parliament, arrived, and seated himself in front of M. de Coislin.  Astonished at this act of madness, M. de Coislin said not a word, but took an arm-chair, and, while Novion turned his head to speak to Cardinal de Bouillon, placed that arm-chair in front of the Chief President in such a manner that he was as it were imprisoned, and unable to stir.  M. de Coislin then sat down.  This was done so rapidly, that nobody saw it until it was finished.  When once it was observed, a great stir arose.  Cardinal de Bouillon tried to intervene.  M. de Coislin replied, that since the Chief President had forgotten his position he must be taught it, and would not budge.  The other presidents were in a fright, and Novion, enraged by the offence put on him, knew not what to do.  It was in vain that Cardinal de Bouillon on one side, and his brother on the other, tried to persuade M. de Coislin to give way.  He would not listen to them.  They sent a message to him to say that somebody wanted to see him at the door on most important business.  But this had no effect.  “There is no business so important,” replied M. de Coislin, “as that of teaching M. le Premier President what he owes me, and nothing will make me go from this place unless M. le President, whom you see behind me, goes away first.”