In plain words
A pure mind is the road to goodness; a pure mind is a mighty power; the pure mind alone is the pearl of the ocean! Do not forget this good word.
Never look at evil, never speak it, never listen to it anywhere in the world; think of the figure of the three monkeys: this is the word that tells what is so.
Students!
In the words of the Upaniṣad, we have come to see that the body is the chariot, the senses are the horses and the Manas is the reins. The principle of the body, the senses and the Manas is, of itself, of no use. However big the horses, however strong the reins, however handsome and fine the chariot, if there is no charioteer, this chariot, these horses and these reins are of no use. So in the journey of life Buddhi is the most important of all. 'Niścayātmaka buddhiḥ,' they said. It is of the nature of firm resolve. In life many problems, many kinds of tangles and upheavals keep breaking out. Now, resolving these problems is every man's immediate duty. But what is the chief principle for this remedy? Buddhi itself. Without the entry of Buddhi, neither our problems nor our tangles can be cleared. It is Buddhi that roots out doubt; that is why they said, 'Buddhi-grāhyam atīndriyam.' Since it lies beyond the senses, its form is of the nature of doubt.
The Bhagavad Gītā has set two banks to its own stream.