How many essays did Charles Augustin Sainte-Beuve write for Causeries du lundi and Nouveaux lundis?

Charles Augustin Sainte-Beuve wrote a total of 640 critical and biographical essays for his series, which were published weekly in Paris newspapers between 1849 and 1869. These essays were subsequently compiled into two major collections:1

• Causeries du lundi: Published in 15 volumes between 1851 and 1862.1
• Nouveaux lundis: Published in 13 volumes between 1863 and 1870.1

These works, which Sainte-Beuve referred to as "chats," were characterized by his meticulous research into the lives, backgrounds, and characters of the authors he examined, establishing a foundational approach to historical criticism.1