In plain words
If we go on trying to purify all of these, our stomachs will waste away. That is why, before taking food, it becomes pure only when we offer it to God. When each one asks himself where God is, a great answer comes from within him too.
Ahaṃ vaiśvānaro bhūtvā prāṇināṃ deham āśritaḥ prāṇāpāna samāyuktaḥ pacāmy annaṃ caturvidham.
There is the fine answer, 'In the form of Vaiśvānara, I dwell in your stomach and digest the food you have eaten.' But He digests it only after we have eaten. Because we eat without offering it to God, many impurities, many faults and many sins enter into it. That is why:
Brahmārpaṇaṃ brahma havir brahmāgnau brahmaṇā hutam.
When we eat in the feeling that it is offered to Brahman, it is not food; it becomes prasāda. All the faults that were in it are removed. By this, the impurities clinging to our Manas can gradually become somewhat clean. Once more, the mirror called the Manas turns clean. But this will not become clean in one day, in one month or in one attempt.
Śreyo hi jñānam abhyāsāj jñānād dhyānaṃ viśiṣyate dhyānāt karmaphalatyāgas tyāgāc chāntir anantaram.
We must practise. Every man who is born is able to gain walking, talking, eating, all of it, only through practice. For this too, a kind of practice is most necessary. If you want a diamond to fetch its price, it has to be cut. If you want gold too to be pure, refined gold, you must burn it many times over and purify it. In just the same way we must refine the nature of our Manas, which is our humanness. By doing this, the dirt that clings to the Manas can be cleared to some extent.
The second is vikṣepa. The Manas is just like a mirror. But as long as we keep moving the mirror, our reflection in it keeps moving too.