Brilliant title: words are to Bojack what water is to fish. The deprivation of the ability to speak cuts off his life support.
Yet, he could speak; but did not realize that he could.
The same way that we could communicate; but did not realize that we could.
Even yet, words to him are a shield of self-protection, masking and diverting attention away from his inner insecurity and desires—the same way that the oxygen helmet protects him from drowning.
Even with the ability to speak, he is not able to communicate.
He has been out of water all along.
