The last of the Six Significant Landscapes by Wallace Stevens:
Rationalists, wearing square hats,
Think, in square rooms,
Looking at the floor,
Looking at the ceiling.
They confine themselves
To right-angled triangles.
If they tried rhomboids,
Cones, waving lines, ellipses—
As for example, the ellipse of the half-moon—
Rationalists would wear sombreros.
Early Stevens is irresistible.