Ten Years Later: The Man in The Iron Mask by Alexandre Dumas Chapter 1 Page 57

The prisoner sighed impatiently, and paused.

“Yes,” said Aramis, “the queen had a second son, whom Dame Perronnette, the midwife, received in her arms.”

“Dame Perronnette!” murmured the young man.

“They ran at once to the banqueting-room, and whispered to the king what had happened; he rose and quitted the table. But this time it was no longer happiness that his face expressed, but something akin to terror. The birth of twins changed into bitterness the joy to which that of an only son had given rise, seeing that in France (a fact you are assuredly ignorant of) it is the oldest of the king’s sons who succeeds his father.”

“I know it.”