It is quite possible that the portrait is of the artist's wife, though this is not confirmed by the rather vague title of this drawing. She appears many times within this sketchbook, with portraits across several decades littered throughout this interesting and informal collection of work. He loved to travel around his local countryside capturing different scenes that could later be turned into full paintings from the comfort of his own studio. In other cases he would work from his home, capturing those he lived with as well as himself from time to time. Finally, he would sometimes make specific trips to art galleries and museums in order to complete study drawings of elements of paintings and also sculptures. Within this particular sketchbook are some recreations of elements from a Rubens painting, for example.
If we look directly at the artwork in front of us, it would have taken up a single page within the sketchbook, and therefore be around 25cm in width. In some cases he would use two pages together for a double spread. Graphite is used throughout each artwork and in this cases he even uses it to write some notes alongside the main drawing. A woman, perhaps middle-aged, leans over, slightly to her right. Detail is kept to a minimum, leaving us able to make out the elements of her face and around her neckline, but nothing more than that. It is the style of her hair that suggests it might be Cezanne's wife, as she is known to have had this style of hair throughout much of her lifetime. Her right shoulder is included briefly here, but generally speaking, this is not one of the more developed sketches found within the book.
Cezanne would sketch throughout most of his life, leaving behind a large number of books in which most of them were contained for a number of years. The new owners of these would break them up into individual pages which would then be more valuable but this has made documentation of his career harder to complete. In recent years there has been some successful attempts at drawing all of these items back together in a single collated list, but it has certainly helped to find a sketchbook such as this one, where everything is still entirely intact, just as left behind by the artist. Cezanne was an artist that constantly strived to improve his technique, but who also genuinely loved capturing moments in his life on paper, way before the rise of photography dominated western society.