大乘起信論裂網疏 4.109

4.109

It is like a lost person who takes east to be west, while the direction has not actually shifted. Sentient beings are also like this: because they are deluded by avidya, they take the mind to be moving, yet it is actually unmoving. If one knows that the moving mind is itself neither arising nor ceasing, one will then enter the gate of tathatā.