each sealed in the belief that they are different · S4
That everybody is identical in their secret unspoken belief that way deep down they are different from everyone else.
Context
The catalog's sharpest c-s fact and one of the novel's master-lines: the very conviction that isolates each person, the secret sense that one is fundamentally unlike everyone else, is the single thing every person holds in common. It is a perfect closed loop of solipsism, in which what everyone shares is precisely the belief that they share nothing, so that even the deepest ground of connection, being the same in this, is invisible to the people standing on it.