Cezanne uses graphite for this artwork, and tends to apply it lightly in most parts of the scene. It creates shadow where uses in a more dark manner, such as where the trees overhang the river as well as where the entrance to the mill has a small walkway. The strokes of graphite are decidely loose, suggesting that the artist worked quickly and without stress, perhaps just trying to commit the scene in front of him to his sketchbook so that he could produce more complex versions of it later on, once he had returned to his studio. Without mainstream photography, quick sketching was the best way for Cezanne to take notes during his trips around the French countryside. He loved to combine nature with architecture, and found the environment around small villages to be the best for this. His time living outside of Paris would bring about a brighter palette and perhaps a more stable mood, as well as bringing an entirely new genre into his work. Aside from this, he continued with portraiture, often producing depictions of his friends and family in order to continue to practice and develop his technical skills.
This artwork was discovered within a collection of seventy drawings, all bound together within a single sketchbook. The item is owned by the National Gallery of Art in the US and features a good variety of sketches, across different genres including a number of portraits as well as landscapes and cityscapes as found with The Mill. The selection cover several decades, which is surprising. Why would he take so long to fill up this sketchbook, when we know that he sketched frequently. This question has never been answered, but one possible answer could be that he lost or stored it for a number of years during which time he purchased some newer sketchbooks in which he worked before they became full.
To see artworks such as The Mill, but with vibrant colour, you should look through some of Cezanne's paintings - including the likes of Chateau Noir, The Sea at l'Estaque and House in Provence. As mentioned, it is entirely rare for you to be able to find huge numbers of buildings within any of his paintings, as he normally went with just a handful of buildings which felt more relaxed and rural. Having spent so much time in Paris, he desired something alternative and found this within Provence later in his career. Even the simple case of living in this environment made him much happier, though the instability in his personal life was never that far away. His character was known to be shy and awkward in his early years, and we can read much about his changing circumstances through the way his style altered over the key periods of his career.