3 ideas
A man in Paris starts visiting the axolotl tank at the Jardin des Plantes every morning. He fixates on the creatures' lidless golden eyes and stillness, becomes convinced they are conscious and silently suffering, and presses his face to the glass. One day he finds himself looking out from inside the tank at his own face on the other side; the man leaves, visits less and less, and the axolotl-narrator hopes the man will write a story about axolotls.
Imagining another creature's inner life intensely enough stops being a way of understanding it and becomes an exchange of places. The more completely the watcher projects a trapped mind behind the animal's eyes, the more the boundary that makes watching possible collapses. The observer gains the inside view only by losing the outside position from which he wanted it.
Once the consciousness is inside the tank, it can see the human but cannot reach him, and the body that walks away carries on, apparently unaware of what it lost. Knowing what it is like to be another creature does not come with any way to say so to someone outside. The only channel left is the hope that the outsider will imagine it himself, which is to say, write fiction.