In plain words
The Manas is the cause, wherever else one may be; home and forest cannot give Mukti. For one who has no Manas, whether he stays in a mansion or stays in the forest, the work is one and the same.
Students!
'Viśvaṃ darpaṇa dṛśyamāna nagarī,' said Dakṣiṇāmūrti. This whole universe appears like a city in the mirror called the Manas. What man has to achieve is not Dharma, artha, kāma and Mokṣa. It is the purity of the antaḥkaraṇa. The very purification of the antaḥkaraṇa is man's chief goal of life. Mano mūlam idaṃ jagat. The whole world rests on the Manas alone. Joy and sorrow, sin and merit, Satya and Asatya, injustice and wrongdoing, whatever takes place in the universe, all of it takes place in the Manas itself. The Manas is the cause of everything. Manayeva manuṣyānāṃ kāraṇaṃ bandhamokṣayoḥ. Of bondage and Mokṣa too, the Manas alone is the cause. Now, this Manas is like a clean mirror. But the Manas has no power of its own. This Manas depends on the senses. It sees through the eyes. Of itself, it cannot see. By way of the ears it hears. It has no power of its own to hear. In just this way the Manas carries out its work through all the senses. That is why every fault the senses commit is painted on the mirror called the Manas. These senses are bound up with a nature made of saṅkalpa and vikalpa. So whose is the fault here, the senses' or the Manas'? In the Manas there are no faults of its own. It is only through keeping company with the senses that the Manas becomes soiled.
That is why all the śāstras have shown that the Manas has three faults. The three are mala, vikṣepa and āvaraṇa. What is mala? Knowingly or unknowingly, we commit faults of many kinds in our life. Not in this birth alone.