In plain words
It is because of Prakṛti that sorrow comes to us. This Prakṛti comes only according to our vision. As long as there is attachment to the body, there is Prakṛti. As long as there is the feeling of Prakṛti, sorrow follows close behind. When attachment to the body goes, then Prakṛti too goes. When Prakṛti goes, then sorrow too is no more. In the waking state there is attachment to the body. Prakṛti is seen. We go through joys and pleasures. In suṣupti, in deep sleep, we do not have even our body. When we do not have even our body, Prakṛti does not appear to us. When there is no Prakṛti, we have no sorrow at all. In the state of sleep alone there is neither joy nor sorrow. In the same way, by thinking of God, we must go on reducing attachment to the body step by step. Only then do the feelings of Prakṛti fade away little by little. When the feelings of Prakṛti cease to be, only then is our sorrow removed. Sorrows and joys are not things that come when we call them. "Will a forest fire burn the neem trees and pass on, sparing the mango trees?" It burns everything down. On the day we reduce attachment to the body, then neither joy nor sorrow will be there.
"The mansions and terraced houses seen in a dream are not there when you open your eyes, are they?" That is why the Upaniṣads said, uttiṣṭhata jāgrata prāpyavarānnibōdhata. O man, wake up from your sleep called Ajñāna. Recognise your own Satya. Though you yourself are nothing other than the embodiment of Satya, you cannot recognise this Satya; you turn round and set out searching, thinking that Satya is somewhere else. It is not outside somewhere. That Saccidānanda is you yourself. There is a King. There is a president. There is a prime minister. In the state of sleep there are no such feelings as "I am the King", "I am the president", "I am the prime minister". But after he wakes up, he is able to say, "I am the King", "I am the president", "I am the prime minister". One who lies in this sleep called Ajñāna, the sleep called the feeling of Prakṛti, does not come to know, "I am the embodiment of Saccidānanda". You, wake up. Wake up on the path of Jñāna. Then it becomes possible to recognise that you are the embodiment of Saccidānanda. As long as you are asleep, you yourself do not know who you are. Only after you wake up does it become possible to recognise your name, your form, your rank, everything. How are we living today? We are living in the sleep of Prakṛti.