The word ‘filth’ conjures up a variety of images. In late-nineteenth-century Spain, industrialization and urban growth provided a fertile breeding ground for such images. The explosion of poverty in the country's cities, along with the growth of related social problems of mendicity, vagrancy, prostitution, alcoholism and the spectre of racial degeneration, generated both fears of social instability and disorder and strategies aimed at containing the threat posed by marginal and deviant social groups. The anxieties sparked by these groups found expression in the images of ‘filth’ – a metaphor for immorality, vice, disorder and deviant behaviour generally – that appeared around them.

The association established in the imagination during that period between ‘immoral’ and ‘infectious’ contagion is reflected in the various discourses of control and science – seen not only in Spain but also elsewhere in Europe – that emerged during this time. In this book I set a selection of Galdós's novels in the context of discourses on public health, domesticity and philanthropy, emphasizing in the process the way in which these were constantly interwoven. My intention is to show how bourgeois and expert-professional ideas on, and attitudes to, deviancy were reproduced by Galdós, and how he positioned himself in relation to these. In doing so, I hope to add a new perspective to the existing critical material on Galdós.

During the course of my research I found especially significant the desire of public health experts – and criminologists – to assume responsibility for, and pronounce on, moral and social matters that did not necessarily fall within their domain of expert knowledge. Their construction of an interventionist medico-moral discourse was based on the link they were concerned to establish between physical and moral health. In medicalizing social issues, Spanish public health experts devoted large parts of their texts to the various aspects of deviancy – mendicity, vagrancy, prostitution, alcoholism, madness and other ‘immoral’ behaviour – that were perceived at the time as ‘social pathologies’, or ‘enfermedades del cuerpo social’.