If we really wish to be free from suffering and experience happiness, it is important to work on the causes. Without working on the causes, we cannot expect to yield any results. Each and every thing must have its own complete cause; things do not appear from nowhere, from the wrong cause, or from an incomplete cause. So the source of all our suffering is our own negative deeds. Negative deeds result from not knowing reality, not knowing the true nature of the mind. Instead of seeing the true nature of the mind, we cling to a self for no logical reason. All of us have a natural tendency to cling to a self because we are so used to it. It is a kind of habit we have formed since beginningless time. However, if we carefully examine and investigate, we cannot find the self.
from the book “Treasures of the Sakya Lineage: Teachings from the Masters”