The Difference Between Spacing Out and Not a Single Thought Arising

Spacing out is when the manas pays deep attention to some matter, with attention almost entirely concentrated on the thing being attended to. The mind consciousness has no thoughts, yet the manas is deliberating very covertly—it is only that the mind consciousness is not generating thoughts. This is a very deep meditative concentration (samādhi); it just depends on how long it can be sustained. If it lasts a bit longer, it will be sufficient to resolve a problem, and one can suddenly gain an insight—the scales fall from one's eyes, and there is no more doubt.

As for the state of not giving rise to a single thought, the mind consciousness has no thoughts, and the manas also has nothing to attend to; the so-called scatteredness is somewhat milder, belonging to a dazed, foolish state. Because there is no problem to deliberate upon, no problem will be solved, there will be no sudden awakening, no inspiration will appear, and no wisdom will be born.