A golden cork is, mirror-wise,
shown by a polished shelf;
yet, even if endowed with eyes,
it could not see itself.

This is because it stands aligned
with its reflected view;
but if it sideways is inclined,
such is no longer true.

O man, suppose you did reflect
straight up, let’s say, in space:
Would this not have the same effect
as in the stated case?

— Christian Morgenstern, 1905