Rats can recognize colors and understand left and right, but they can't put the two together to locate a biscuit left of the blue wall in a maze. They can't connect the color with going left to find a biscuit. It's 50/50 whether they go right or left.

Children up till six years of age are also like this, except that they're constantly babbling words. Then around six, they're able to string different concepts together to say something like, "The biscuit is left of the blue wall", and understand it.

Now when adults are tasked with reciting back words they're listening too, they lose the ability to make sense of "left of the blue wall". What this suggests is that language is a means by which different regions of the human brain communicate with each other. You have one region in the visual cortex that recognizes blue. And another that recognizes a biscuit. You also have a spatial understanding of left and you know what a wall is. When someone says, "The biscuit is left of the blue wall", those different regions of the brain are able to communicate with one another, leading us to a world of understanding not available to small children and rats.

I thought it was an interesting theory of language. That it hooks up different regions of the brain with different conceptual understanding, providing us with a combinatorial explosion of meaning. They went on to discuss Shakespeare's genius and all the common phrases he invented by shoving different concepts together.