In plain words
The mind is not merely something like a blank sheet of paper. This mind is bound up with the impressions of many births, the marks of karmas. It shows itself as the reflection of the Ātma. The greatest wealth we have in this world is this very principle of the Ātma. “The richest wealth is Atman,” they said. For us to recognise such a principle of the Ātma is very hard. “Ātma + mind = man,” they said. “Man − mind = Ātma,” they said. So the mind alone is the root cause of both. Not of these two alone: the mind is the root cause of creation itself. The mind alone is the root cause of everything. That is why they said, “Manayeva manuṣyāṇāṃ kāraṇaṃ bandhamokṣayoḥ.” It does not bow in the least to these circumstances. Whatever the circumstances, if there is good thought in a man, his life will be a divine life. So in every man too, it is essential to enquire into this thing called good thoughts, to recognise what it is about, and to act on it.
Every man has to enquire, exactly and with a broad outlook, into the law of thought and its workings. For such good thought, good company is needed. This good company drives away the bad thoughts one had before and spurs on good thoughts. Many books have been teaching many ideals, with many parables too. Ratnākara was a murderer. He tormented travellers in many ways and used the wealth he robbed from them to keep his family. That Ratnākara, through his contact with the seven ṛṣis, got rid of his bad feelings and bad thoughts and so became Vālmīki, the first poet. The seven ṛṣis too taught that Vālmīki was the giver of the śloka, and that God is the giver of the worlds.
Then in the Buddha's time too, Aṅgulīmāla. He was a great evildoer. He too, like this Ratnākara, tormented travellers and amassed wealth of many kinds from them; and not stopping at that, he cut off their thumbs and wore them as a garland. A cruel man. But that cruel Aṅgulīmāla, through his contact with the Buddha, was transformed into a sādhaka.