The Hossō School’s position was that two categories of Buddha nature could be identified: the ribusshō, which all men possessed, and the gyōbusshō, which only a few possessed. The first was the Buddha-nature as absolute. Since the absolute was the basis of all phenomena, and since all sentient beings were ultimately dependent on the absolute, all were said to possess the ribusshō. However, Hossō scholars argued that the absolute was static; it did not actively participate in the phenomenal realm. Consequently, the ribusshō did not enable a practitioner to attain Buddhahood. When a sūtra stated that all sentient beings possessed the Buddha-nature, it indicated only that all had the ribusshō, not that all could attain Buddhahood.

The potential of some sentient beings to attain Buddhahood was explained by postulating a second type of Buddha-nature, the gyōbusshō or Buddha-nature of practice. The gyōbusshō consisted of untainted seeds (muro shuji) which were stored in the eight or basic consciousness (arayashiki, Skt. ālaya-vijn͂ana). These seeds were said to have existed from the beginningless past. If a person possessed them, he could attain Buddhahood. However, if he lacked untainted seeds, he could not create them no matter how diligently he practiced or studied. A person without the gyōbusshō could therefore never attain Buddhahood. Hossō School monks interpreted statements in the sūtras that only certain people could attain Buddhahood as referring to the possession of gyōbusshō by those people. Since not everyone had the gyōbusshō, some sūtras contained statements that not everyone could attain Buddhahood.