In the following study, which is part of a wider study of shapeshifting, the concept of ‘involuntary’ shapeshifting will be discussed and compared across literary evidence in Early Medieval Irish and Old Norse narrative traditions. The wider study also considers two other concepts of shapeshifting, namely ‘voluntary’ and ‘genetic’. By categorising shapeshifting into these three categories, the literary evidence can be analysed and compared in a consistent way.

When examining shapeshifting, or metamorphosis, it is important to distinguish between metaphorical and literal changes. The literal representations are situations where a character is described as changing shape, not just assuming some animalistic traits. Metaphorical is defined as situations in which the author of a text has used animal imagery to describe or explain human behaviour. Caroline Walker Bynum has identified two types of shapeshifting, the first being metempsychosis, i.e. ‘body hopping, body exchange, or body erasure’, the second being metamorphosis, i.e. the ‘change of one body into another or change of species’. Metempsychosis happens when the soul, or an equivalent interpretation of the soul, leaves the body and inhabits another body or vessel. The soul assumes the physical exterior of the vessel, while keeping the mental interior of the original vessel. Metamorphosis is defined as the whole physical body changing into another, or changing species. In some cases, the mental interior will change too, as with the change of species, where some of the animal characteristics not previously inherent in the shapeshifter are assumed. In others, they remain the same and only the exterior changes. The capacity of human language is often lost when a change of species occurs, taking the shapeshifter to a bestial level. The examples used in this study show cases of metamorphosis only.