Meanings of incommunicable thoughts in English

Their conversation, however, was fragmentary, as if each were deep in incommunicable thoughts.

She wanted to indulge in solitude her wild, passionate dreams, her secret, deep, incommunicable thoughts.

But with a faltering hand I try to express one of many incommunicable thoughts about the hero who has departed.

Apparently, they were scarcely better able to understand each other than if they spoke in different languages, and each took refuge in incommunicable thoughts.