SB 5.11.8
gunanuraktam vyasanaya jantoh
ksemaya nairgunyam atho manah syat
yatha pradipo ghrta-vartim asnan
sikhah sadhuma bhajati hy anyada svam
padam tatha guna-karmanubaddham
vrttir manah srayate ’nyatra tattvam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When the living entity’s mind becomes absorbed in the sense gratification of the material world, it brings about his conditioned life and suffering within the material situation. However, when the mind becomes unattached to material enjoyment, it becomes the cause of liberation. When the flame in a lamp burns the wick improperly, the lamp is blackened, but when the lamp is filled with ghee and is burning properly, there is bright illumination. Similarly, when the mind is absorbed in material sense gratification, it causes suffering, and when detached from material sense gratification it brings about the original brightness of Krsna consciousness.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
It is therefore concluded that the mind is the cause of material existence and liberation also. Everyone is suffering in this material world because of the mind; it is therefore proper to train the mind or to cleanse the mind from material attachment and engage it fully in the Lord’s service. This is called spiritual engagement. As confirmed in Bhagavad-gita (14.26):
mam ca yo ’vyabhicarena
bhakti-yogena sevate
sa gunan samatityaitan
brahma-bhuyaya kalpate
“One who engages in full devotional service, who does not fall down in any circumstance, at once transcends the modes of material nature and thus comes to the level of Brahman.”
We should engage the mind fully in Krsna conscious activities. Then it will be the cause of our liberation, for our returning home, back to Godhead. However, if we keep the mind engaged in material activities for sense gratification, it will cause continuous bondage and will make us remain in this material world in different bodies, suffering the consequences of our different actions.