The discernment of the eight mind-kings (the eight consciousnesses) is realized through various mental factors (caittas).

The discernment of the eight consciousnesses, the kings of the mind, is accomplished with the aid of the mental factors (caittas). Without the operation of the mental factors, the eight consciousnesses, the kings of the mind, would have no capacity for discernment; discernment is the auxiliary function of the mental factors assisting the mind consciousness. For example, the discernment of the mind consciousness requires the manaskāra (intention) mental factor to direct attention toward the object-aspect, the sparśa (contact) mental factor to make contact with the object-aspect, the saṃjñā (perception) mental factor to grasp and seize the mark, the vedanā (feeling) mental factor to receive and experience it, and the prajñā (wisdom) mental factor to discriminate with wisdom. At times, the samādhi (meditative concentration) mental factor is needed for the power of focused attention; afterward, the mind consciousness must have the power of determination (adhimokṣa) with respect to the object-aspect. At times, the assistive and evocative functions of the chanda (desire) mental factor and the smṛti (mindfulness) mental factor are also required, and the participation of wholesome and unwholesome mental factors may also be involved, endowing the discernment with a certain wholesome or unwholesome character. Therefore, the discernment of the eight consciousnesses, the kings of the mind, is realized through various mental factors; without the mental factors, the mind consciousness can accomplish nothing.