Perhaps an illustration would make this clearer. Picture a hand holding a medicine dropper that drips colored dye into a glass filled with clear water. The empty glass is the base-consciousness, or eighth consciousness ( citta); it has no particular function except to retain whatever amount of water you put in it. The water inside of the glass, being pure and clear before the dye taints it, corresponds to the primary consciousnesses ( vijnana), or the six consciousnesses. The hand and its action of dripping dye into the glass represent the self-grasping nature of the faculty of mind, or seventh consciousness. The dripping dye, conditioned by this self-grasping, refers to dhatus— thoughts, feelings, and their corresponding symbols. When the dye (dhatu) enters the glass, the clear water (six sense consciousnesses) is tainted by the colors of thoughts and feelings. If this were not to happen, the eye consciousness would act purely like a camera, the ear consciousness purely like a recorder-we would perceive all things ‘as they are.’ But for ordinary sentient beings, the seventh consciousness, the self-notion, is forever conditioning and coloring how we interact with others and the world, tinging our experience with all sorts of colorings.

All of these aspects of mind are inextricably interconnected. None of them can exist by themselves. Thinking and feeling both rely on symbols ( dhatus). The capacity to feel and think must be stored in the repository base-consciousness ( citta). The very reason that the self-grasping mind faculty continues is due to the karmic momentum stored in the base consciousness. In turn, these karmic imprints stored in the eighth consciousness manifest when proper causes and conditions arise from the interaction between the primary mind ( vijnana) and the environment.