The study of symbols - language, for example - quickly becomes very deep. AND, humans are the only creatures that can make use of them, as far as I know.
I needed a filler course in college and a class called 'Semantics' looked a perfect fit, AND the text (something about symbols) was only about 35 pages. Yikes! By the end of the semester I was still struggling to finish - and it changed my whole way of thinking - or seeing... something like that. As language it is a study of cosmology, as grasped by the human brain.
Speaking of symbols, someone can tell corn pop we found another meaning for roach
roach (n.)
street names
Synonyms: R-” / Mexican valium / rophy / rope / roofy / forget me drug / circle