The parts I am finding most interesting are of the description of language as a source of conceptualization and abstraction in our though processes, which allows for the creation of signs and the transmission of signs between individuals.
This world of signs we live in, as a separate distinguished mode of perception than is experienced by sentient beings which do not think in these sorts of abstractions and conceptualizations.
We inhabit a world full of abstractions, impossibilities, and paradoxes. We alone brood about what didn't happen, and spend a large part of each day musing about the way things could have been if events had transpired differently. And we alone ponder what it will be like not to be. In what other species could individuals ever be troubled by the fact that they do not recall the way things were before they were born and will not know what will occur after they die? We tell stories about our real experiences and invent stories about imagined ones, and we even make use of these stories to organize our lives. In a real sense, we live our lives in this shared virtual world. And slowly, over the millennia, we have come to realize that no other species on earth seems able to follow us into this miraculous place.
We are all familiar with this facet of our lives, but how, you might ask, could I feel so confident that it is not part of the mental experience of other species--so sure that they do not share these kinds of thoughts and concerns--when they cannot be queried about them? That's just it! My answer which will be argued in detail in the following chapters, has everything to do with language and the absence of it in other species. The doorway into this virtual world was opened to us alone by the evolution of language, because language is not merely a mode of communication, it is also the outward expression of an unusual mode of thought--symbolic representation. Without symbolization the entire virtual world that I have described is out of reach: inconceivable. My extravagant claim to know what other species cannot know rests on evidence that symbolic thought does not come innately built in, but develops by internalizing the symbolic process that underlies language. So species that have not acquired the ability to communicate symbolically cannot have acquired the ability to think this way either.
I suppose I'm trying to understand scientifically the nature of this sign-based reality, and maybe gain some insight into it.