I'm also curious what you could possibly mean by this. I think you either misunderstand the quote, or are referring to something mystical that most people wouldn't buy into.

Can you explain what you mean by the experience of true union? Do you mean perfect communication through words and actions, or some connection on a higher level, perhaps spiritual or drug-induced?

Also, even if, for certain pairs or small groups of people, it is possible to achieve a truly deep level of understanding, in general the principle is still sound and arguably the most important application is to those whose universes are the most foreign to yours.

> The experience of true union exists

> Sensations, feelings, insights, fancies - all these are private and, except through symbols and at second hand, incommunicable.

I'm sorry but what? Can a union of a blind person and a person with sight communicate "redness" to the blind person such that the both have the exact same representation of red inside their head?

If you have anything on this, I would love to read it.

Not responding to the parent but these links:

https://en.m.wikipedia.org/wiki/Bouba/kiki_effect

http://www.npr.org/programs/invisibilia/378577902/how-to-bec...

Might shed some light on your question.