The field of esoteric material sciences was quite interesting as he began going through the foundational premise.
The basic premise of the field relied on the distinction between normal and esoteric materials. Normal substances and compounds were those compounds whose properties were understood by science. These included things like water, iron etc.
Although not everything about these substances was entirely understood on a fundamental level, this was the case with all substances including esoteric substances as well.
Esoteric substances were substances and compounds whose fundamental properties were not only entirely not understood but also seemed to defy the framework of theoretical sciences that existed so far.
Rui was aware of this, but there was more that he wasn't aware of. There were multiple scientific theories that tried to explain the existence of esoteric substances and why they were the way they were, and how they ought to be categorized.
