Published on "Barricade Day," June 6, 2012.
When Marius was eight years old, his Aunt Gillenormand gave him his first notebook, and instructed him in how to write in it. She encouraged him to write regularly – one of the few things Marius learned from his aunt.
As he grew older, he found that didn't like the rigid structure of a diary. So instead of writing to an imaginary recipient about what he did each day, he simply wrote down some of his more important thoughts. Eventually he learned to do this as soon as ideas occurred to him. To save time, he developed the habit of carrying a notebook and a pencil in his coat pocket when he went out.
Writing things down helped Marius to remember them. He also found that he liked looking back to see what thoughts had entered his mind only to be forgotten until he refreshed his memory.
Marius took very little with him when he left Grandfather Gillenormand's house. As he packed his bags, he found he could not bring himself to leave behind or destroy his old notebooks. They were a part of his past, of his life, that he wanted to hold on to.
During his times of loneliness, his current notebook proved to be his most reliable friend. Instead of talking to himself (as most people do), Marius wrote to himself. Here he examined and organized his thoughts. This helped him to think logically and deeply.
Marius was not as much of a philosopher as his friends and fellow students. But what few philosophies he produce, he wrote down in his notebook.
Writing was something he had in common with Jean Prouvaire, the poet in the Friends of the ABC. Grantaire ranted about it, alternately praising and mocking how they kept their thoughts in their pockets and sorted through them at the end of the day, or week, or year. Marius didn't mind, or if he did he didn't show it; but from then on he kept the habit a bit more private, though he took care not to be secretive about it. He never wrote down anything he might be ashamed of.
Marius later thought that the notebook must have been a Godsend, because it became instrumental in communicating with Cosette. He entrusted to her pages from his most recent notebook, revealing his heart to her before introducing himself to her.
It also proved less romantic and more practical, such as when he wrote his address down so he could be identified if found dead or unconscious at the barricade.
Twice Marius' notebooks, imparted to him by Aunt Gillenormand, saved his life.