The Sarvastivada School and the Yogacara (Mind-Only) School hold many different viewpoints on the interpretation of causality, but the ones elucidated by the Mind-Only School are the more comprehensive within the context of the relative truth. The Yogacara School asserts that everyone has a mental continuum from beginningless time until the attainment of enlightenment. This mental continuum sometimes has the five consciousnesses of eyes, ears, nose, tongue and body, but sometimes not. No matter how it manifests itself, a permanent existence called the substrate consciousness is present at all times. Whenever karma is committed, a karmic seed is planted in the alaya consciousness.

[Excerpt from Luminous Wisdom Book Series ~ The Right View : On Cause and Effect]