In plain words
A tree can be straightened so that no bend remains; a stone can be dressed true and straight; can you straighten the mind so that no bend remains? Hear this, heroic son of Bhārata!
Students!
The mind is very strange. The mind is very swift. The mind is very fickle. Mighty in strength is the mind. While the man is here, the mind runs off some thousands of miles. In a single moment it travels thousands of miles and can see the sights there. ‘Cañcalaṃ hi manaḥ kṛṣṇa pramādi balavad dṛḍham. How can we hold back a mind so very firm, a mind so very fickle, a mind so very strong?’ said Arjuna.
This mind has two natures. One is the animal nature. The second is the human nature. We must try to recognise what the animal nature and the human nature are. Falling under the six inner enemies called desire, anger, greed, pride and envy, yielding to many vāsanās and thereby behaving merely like a beast, the mind forgets its humanness, takes the wrong road and sinks down into a beast. The second. Making good use of the intellect, the standing, the course and the wealth God has granted, it thereby takes up a humanness that is divinity, and thereby goes on doing many good turns for the country. The mind itself is the root cause of this good and bad. The goodness that is in the mind is in nothing else. The badness that is in the mind is in nothing else either. It is as bad as it is good.
The mind is in fact very pure. Through the fault of company, this mind takes shape as good and bad. Here is a clean newspaper. When you wrap jasmine flowers that give a sweet fragrance in this newspaper, the jasmine's fragrance passes to the newspaper.