I don't care whether the building is a factory or a mill; whether it makes automobile tires or silk shirts. It is the romantic mass of the building, its placing relative to the landscape and the life in and about it that count.-Robert Spencer

The mills of Bucks County intrigued Robert Spencer, inspiring a series of paintings during the 1910s. The artist's interest in these mills was piqued around 1910 when he moved across from the William Maris Silk Mill, which had been built in 1813. Its dilapidated condition prompted Spencer to wonder about the dismal working conditions inside.
The Maris Silk Mill, along with the Richard Heath Grist Mill, are the most common subjects of Spencer's mill paintings, which typically capture the gloomy, exhausting lives of the immigrants who labored there. Through his use of muted colors, especially dull shades of gray and brown, Spencer conveys this sense of dreariness. In one of the most famous paintings of this series, Grey Mills, Spencer depicts women and children flocking into the Maris mill to begin work. The painting's composition emphasizes the building's deterioration and bulk, showing its frayed gabled roof and massive height. The small, bent figures of the workers, in comparison, appear anonymous and oppressed.
For Spencer the old mills appeared romantic because, built over one hundred years earlier, they represented a way of life that, in his day of rapid industrialization, was quickly becoming extinct. In spite of the paintings' bitter nostalgia, they never lapse into sentimentality. Capturing the gloom and strain of these laborers' lives, Spencer refused to idealize a subject that, however quaint, was cruel.