This thesis investigates the oft-overlooked influence of the classifier's input during the assignment of library classifications and draws upon cultural transfer theory to shed light on the underlying principles that guide the process. Classifiers' personal knowledge, experience, and beliefs, have a critical role in determining the 'aboutness' of a work and its subsequent classification. To explore this theory, this research employs a dual-methods approach, using qualitative analysis of past literature contrasted with a data set formed through a real-world reclassification project at The Swedish Institute in Rome (ISVRoma) using the Library of Congress Classification scheme (LCC), with classifications in the catalogue of the American Academy in Rome (AARome) used for comparison. The resultant data provides a basis for examining the classifier's cultural input and the manifestation of cultural transfer theory in library classification. The findings of this thesis reveal the dynamic nature of classification, which is not a mere static or administrative task, but rather an evolving process deeply embedded in the societal and cultural context. Classifiers are found to act as interpreters, translators, and shapers of knowledge, bringing a profoundly human element to knowledge organisation and retrieval. The classifiers' craft, therefore, extends beyond the implementation of a systemic and controlled vocabulary and involves an active contribution of their knowledge and experience. This contributes to the overall flexibility and adaptability of the classification system. The thesis also underscores the necessity of reassessing our understanding of library classification systems, especially in light of AI's increasing role in this field.