If you want to get really ancient, you could research some of Plato's writings. He talks a lot about what 'reality' is and how it is defined, he does theorise on a few concepts of language. Or maybe Joachim Du Dellay (hope that spelling is correct). I'm not THAT familiar with earlier philosophers, sorry. But anyway, good luck! I'm sure you will come across more people you can look into as you research.
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