首楞嚴義疏注經 9.56

9.56

「是人既以生滅為因，不能發明不生滅性，初半劫滅、後半劫生。如是一類名無想天。」

"Since this person takes arising and ceasing as the cause, they cannot illuminate the nature of non-arising and non-ceasing: during the first half-kalpa it is extinguished, and during the second half-kalpa it arises. One such category is called the Heaven Without Thought."