In the earlier study a candle holder is visible, and the flame is reflected in the bowl. Hockney believes that many of the Old Masters used optical equipment to assist in their painting, and suggests that Wright may have used lenses to transfer the image to paper rather than painting directly from the scene, as he believes the pattern of shadows thrown by the lighting could have been too complicated for Wright to have captured so accurately without assistance. It may be observed, however, that the stand on which the pump is situated casts no shadow on the body of the philosopher, as it could be expected to do.
A previous study shows a candle holder visible in the background, with the flame reflected in the bowl. Hockney hypothesizes that many Old Masters used optical aids to enhance their work, suggesting Wright may have relied on lenses to transfer images onto paper rather than painting directly from the scene. Notably, the pump stand supporting the philosopher casts no shadow on his body.