俱舍論頌疏論本 2.10

2.10

Explanation: Those bound to the desire realm are fully eighteen. Those bound to the form realm are only fourteen, excluding the objects of smell and taste, and the consciousnesses of nose and tongue. Smell and taste are excluded because their nature is material food (kavaḍīkārāhāra); in the form realm there is no material food, and therefore no smell or taste. Nose and tongue consciousnesses are excluded because they lack cognitive objects: nose consciousness takes smell as object and tongue consciousness takes taste as object; since smell and taste are absent, nose and tongue consciousnesses are absent.