Subject of labor, or object of labor, is a concept in Marxist political economy that refers to "everything to which man's labor is applied." (Institute of Economics of the Academy of Sciences of the U.S.S.R., 1957) The subject of labor may be materials provided directly by nature like timber or coal, or materials that have been modified by labor. In the latter case, the subject of labor (e.g., yarn in a textile mill or semi-conductor chips in a computer assembly factory) are called raw materials.