Final answer:
The unique aspect of Lester's 'Young Flute Player' is its combination of a genre scene and a portrait, showcasing the artist's skillful use of light and shadow to define the subject.
Step-by-step explanation:
The artwork by Lester titled Young Flute Player is unique because it is a combination of a genre scene and portrait. This painting portrays a young musician, capturing the essence of childhood and music in a single piece. The striking contrast generated by the overly white face of the boy on one side due to bright light, and the deep shadows on the other, epitomizes the artist's expertise in using light and shadow to define the subject's features and the surrounding objects, such as the chair, clothing, and musical instruments, which are all well defined despite the use of many tones of brown and gray.