What does “一切俱” (universally accompanying) refer to among the five universal mental factors?

In the five universal mental factors (pañca-sarvatraga-caitasika), "accompanying everything" means that the five universal mental factors accompany all consciousnesses and accompany all dharmas. As long as any consciousness is operating, the five universal mental factors must be operating as well; apart from the five universal mental factors, a consciousness cannot operate, cannot exist, and cannot engage in discriminating activity. Therefore, on all dharmas there are also the five universal mental factors of consciousness, because on all dharmas there is at least the operation of the eighth consciousness and the seventh consciousness, and the five universal mental factors necessarily accompany the operation of these two consciousnesses.

That the five universal mental factors arise together with one another means that these mental factors are born and operate as a group. For example, when the eighth consciousness gives rise to a dharma, all the mental factors of the five universals must accompany the operation of the eighth consciousness from beginning to end, without a single one missing. But this is not necessarily so for the sixth and seventh consciousnesses. After the sixth and seventh consciousnesses direct attention (manaskāra), if they are not interested, there will be no contact (sparśa)—especially in the case of the seventh consciousness, the manas. After contact, feeling (vedanā) does not necessarily follow—especially in the case of the seventh consciousness, the manas. After feeling, perception (saṃjñā) does not necessarily follow—especially in the case of the seventh consciousness, the manas. After perception, deliberation (cetanā) does not necessarily follow—especially in the case of the seventh consciousness, the manas. If the manas's mental factors do not continue to operate, the six consciousnesses cannot appear; even if they do appear, they will cease and stop operating. In particular, if the manas's deliberation mental factor does not manifest, none of the six consciousnesses can appear. From this one can see the sovereign ruling position of the manas—how great His power is.

The Buddha's dharma is profoundly deep; if one's contemplation is even slightly lacking in power, deviations will arise. Yet the vast majority of people's contemplation is flawed, and they are unable to discover this themselves, nor are they willing to admit it. Many people, precisely because their own contemplation lacks power, have no alternative but to accept the words of famous figures with one hundred percent faith, relying on a ready-made answer, taking it as final, believing this to be reliable, and not even knowing when they are wrong. This is an extremely widespread phenomenon in the Buddhist world today.