The Basis Consciousness

The passage below from the Sutra Explaining the Thought is one of the earliest descriptions of the "basis consciousness" (alaya-vijnana), a doctrine that was central to the Yogachara school and that was also influential in other Mahayana countries, particularly Tibet and China. The basis consciousness is the most fundamental level of mind, and it is said to be comprised of the "seeds" of past actions and mental states.
The seeds become part of the continuum of the basis consciousness, which is moved along by their force. If one cultivates positive actions and thoughts, for example, one's mind will become habituated to positive actions and thoughts. The converse is true of those who engage in negative actions and thoughts.
Under appropriate conditions, the seeds give rise to corresponding thoughts and emotions, and these are the phenomena of ordinary experience. Mind and its objects are said to arise together, and so there is no substantial difference between subject and object. Because of this, phenomena are said to be "cognition-only" (vijnapti-matra), meaning that all we ever perceive are mental impressions, and not things in themselves.
[Buddha:] `Initially in dependence upon two types of appropriation--the appropriation of the physical sense powers associated with a support and the appropriation of predispositions which proliferate conventional designations with respect to signs, names, and concepts--the mind which has all seeds ripens; it develops, increases, and expands in its operations....
`Consciousness is also called the "appropriating consciousness" because it holds and appropriates the body in that way. It is called the "basis consciousness" because there is the same establishment and abiding within those bodies....It is called "mind" because it collects and accumulates forms, sounds, smells, tastes, and tangible objects.