Mind, in Mahayana Buddhism, is always the absolute. But this absolute or essence for us is only still an unawakened immediacy. It has yet to fully recognize itself. While Bodhidharma will say, This mind is the Buddha, he doesn’t say the mind of life and death is, or the defiled mind is the Buddha. We still must, on our own, make it to the summit of Mind. This is not a journey outside of us. Far from it. Our very mind right now has the potential to know itself, that is, to become Buddha or awakened. Connected with this, enlightenment or the awakening of mind to itself comes after the sublation of error. This involves mind overcoming its attachment to its phenomena which keeps it weak and deluded.
In order to awaken itself, mind must take a path in which it will have to set aside the untruths of itself before it reaches itself symbolized by the Bodhi-tree. The journey on this path consists in mind encountering its untruths and setting them aside which is also mind's suffering. But it is also mind's purification in which it is harmonizing and advancing towards itself which will then be the Bodhi Mind.
Ultimately, when mind has acquired the ability to always turn to itself (samâdhi), instead of always facing and depending on its phenomenal arisings, it is the Mind that is absolute Mind or Buddha Mind. Nothing can defile it ever again. This is the real beginning of the Bodhisattva’s path which will continue to unfold the richness of Buddha Mind until Mind turns all of phenomena; no longer being turned by phenomena.