octagonal piece of jade with hole in middle
琮 refers to a specific ancient ritual object: an octagonal jade piece with a central hole. Its meaning is narrow and concrete, centered on this ceremonial jade artifact.
琮 combines 王 (jade) with 宗, which likely provides the sound and may relate to ancestral or ritual contexts, fitting the object's ceremonial use. The exact historical development is uncertain.
The left side 王 (jade) tells you it's a jade object. The right side 宗 suggests a ritual or ancestral hall. Picture an octagonal jade piece with a hole, used in ancient ceremonies.
For ソウ, imagine a soul (ソウ) of an ancestor passing through the hole in the jade during a ritual: soul -> ソウ.