A great article by novelist Lawrence Norfolk:

“A writer’s notebook is a junkyard; a junkyard of the mind. In this repository of failed attempts, different inks speak of widely-spaced times and places, the diverse scrawls of varying levels of calligraphic awkwardness, lack of firm writing-surfaces, different modes of transportation. “

Here’s a photo of one of his own notebooks:

 

Read more at BBC News – Writers’ notebooks: ‘A junkyard of the mind’.