Engels argues that industrialization is directly responsible for the poor living and working conditions he observed in Manchester, particularly the poverty of the working class. He claims that these circumstances are unique to the "industrial epoch" and describe them as "horror and indignation." Manchester's rapid population growth was aided by the development of factories and mass production as a result of Manchester's industrialization. This was due to the influx of factory workers. The filthy and crowded living conditions of the working class demonstrate this. Engels asserts that industrialization also led to wage declines, an increase in unemployment, and "child slavery," or the forced labor of children in factories. Engels asserts that all of these conditions are the result of the industrial age.