Great Sky Beyond Effort Tantra says:
Due to inborn unawareness, heart essence itself
Though ever here, goes unrecognized.
Through beginningless delusion
Samsara is engaged, wherein
Attracted to external objects and
With wrongful imputation
We wander the six realms of rebirth
Incurring various dissatisfactions,
Since grasping at objects is deeply ingrained.
The Root Sutra of Primordially Existent Phenomena (Ye srid bon gyi mdo rdza) says:
Though in no way different in terms of the base
Adventitious unawareness and primordial wisdom
Appear as any exalted qualities or degraded delusion; still
They move not one single iota from the base.
Though the base is utterly without delusion
Mental delusion modifies the base, and so
Not seeing the very base due to causes and conditions,
That very base appears as the bon-phenomena of samsara
Collection of Jewels Sutra (‘Dus pa rin po che’i mdo) :