It can be argued that the basis of thinking is never symbolic -- it is always visual. We ourselves — as in "our rational mind", our rational Self — understand something by visualizing it, by creating a three-dimensional c̸o̸m̸p̸u̸t̸e̸r mental model of it, so, in effect, we could run a simulation of that portion of reality in our head. <== And that is how we know things, by acquiring a mental model for it.
"To know your Self, think for yourself."
Only thereafter we turn to symbolic language in order to describe what we saw to others, to share our understanding (just as we use symbolic language to describe -- and, yes, share! -- our actual experiences). The reverse must be true as well -- we can really understand what we have been described with words when we visualize and re-enact that story in our imagination, re-living, to some extent, the storyteller's own experience.
Or, as Morpheus' would put it...
Note the difference between rational understanding/knowing something and having (an irrational) idea of it. Some things can never be known -- for example, no one can know what is a chair — tho most have a pretty good idea of a chair. "Simple ideas" like that (using John Locke's term) are always a product of the neural net in our sub-consciousness. And while the latter can have a very good idea of many things, ultimately it knows nothing and understands nothing -- because, relying on experiences alone, it has no concept of the "outside". And with no concept of objective reality, there can be no concept of truth either!
In a way, our subconsciousness never knows, it merely pretends that it does -- "... for there is no truth in it. When it lies, it speaks its native language." (John 8:44)
That's why, ultimately, -- and it was true for Jesus, as it was for Socrates -- "I cannot teach anybody anything. I can only [try and] make them think."