Digression:
Consider for a mement the way we talk about flounders.
In their deep structure flounders are vertically swimming fish, each
equipped with a rotation variable marked plus or minus left. A maturing
flounder marked "alpha-left" undergoes two transformations:
- one by which it starts swimming on its alpha-left side,
- another by which its alpha-left eye migrates over its head to the minus-alpha-left side of its
head.
What in the surface structure of a mature flounder is its top
corresponds to the left or right side in the deep structure; in fact,
our choice of the words top and bottom are determined by the surface
structure, left side and right side by the deep structure. The
summer flounder swims on its left side, the winter founder swims on
its right side (or else the other way around). We can say of the summer
flounder that its top is its right side and its bottom is its left side.
From Lecture 2, "Space"
of Fillmore's Deixis Lectures