だ versus な in causal subordinate clauses


Why do causal subordinate clauses ending in -から take だ as a means to connect
nouns and な adjectives (e.g. 日本人だから), whereas causal subordinate clauses
ending in -ので take な (e.g. 日本人なので)?

I read that だ derives from て+ある, whereas な derives from に+ある, but why would
one causal conjunction require で, whereas another one requires に?

Just trying to make sense of it all…

Thank you!




This explanation is tautological but I just have to say it's because から
follows a terminal form, which of the copula is だ while の is a kind of noun,
which needs an attributive form to be modified, which of the copula is な.

Their etymology has nothing to do with this issue.




This explanation is tautological but I just have to say it's because から
follows a terminal form, which of the copula is だ while の is a kind of noun,
which needs an attributive form to be modified, which of the copula is な.

Their etymology has nothing to do with this issue.

