The textbook gives minority (sighar) as an example of an operative feature within historical discussions of guardianship. It connects an established juristic treatment of one minor with the question of extending a ruling to another case sharing that characteristic.
«الصغر إجماعًا»
Minority is treated here as a cause by consensus.
Terms such as ghulam, jariyah, and marriage guardianship belong to a particular classical legal context. They should not be transformed into timeless or universally agreed contemporary legal instructions without further evidence. The methodological point is that ijma‘ can help establish a legal cause.