Theory stating that any tree that looks still (especially if it grows upside down, its head planted in heaps of (empty) shells) is only so for the one who is contemplating it.
Theory which asserts that it does not only depend on how a person looks at it but also on the time he lives in (especially if he, who is probably capable of moving, seems to display a state of wandering (strolling, walking or roaming).
Theory best known for its famous syllogism raising the question of time but also that of space, of direction and of meaning:
The tree is still or else it looks still
because it lives in a time different from ours
yet the man who takes time, sees the trees walking.