{ 1 } - is never applicable, since our senses are infallible.
{ 2 } - is a metaphor.
{ 3 } - suggests the transcendental realist doctrine that we perceive, not the thing in itself, but only appearances.

It's like your senses TELL you some specific statement -- and this statement can be either true or false.

This suggests that there is an intermediary (sense data) between us and the world. And so the metaphor softens us up to accept the "official doctrine" -- that we directly perceive sense data and not material objects. The metaphor also suggests that we should be more skeptical about our senses.