Onychomancy
Onychomancy describes divination through fingernails, including images or reflections observed on them in historical accounts.How to approach it
Understanding this practice involves identifying the period, place and source describing it. A preserved object, a literary account and a later reconstruction offer different kinds of information.
An important distinction
It does not diagnose nail marks or predict illness.
An example to explore
When reading an old account, distinguish the reflection described from any medical interpretation the text cannot justify.
Taking the idea further
To explore further, compare the related concepts and note differences in material, procedure and interpretation. If you open a related tool, read its own rules; sharing a symbol does not mean carrying out the same practice.