In your mind's calm
The four types of Samadhi that we discussed are vitarknugama samadhi (the calm of mind that you get from special logic), vichrnugama samadhi (equanimous state where you are aware of the thoughts, yet they are not disturbing you), anandnugama samadhi (blissful state) and asmitnugama samadhi (deep experience of meditation with just the awareness that you are).
Now, how to achieve these states of Samadhi? The next sutra says it is very simple.
Viramapratyabhyasapurvaha samskarasheshonyaha (Sutra 18) meaning the practice of deep rest consciously happens in some people naturally due to old impressions. Just by doing something, you cannot achieve this awareness. You cannot bring up the intelligence or alertness in you by effort. This happens without effort, by relaxation, by reposing in the self.
Unconscious rest is sleep, which we are forced by the nature. You are not resting then, you are forced to rest. You are so tired and nature is pulling you down and forcing you and making you rest. Real rest happens only in deep meditation because you are consciously resting then. You allow yourself to rest. Do you see the difference? Sleep is putting you to rest but meditation makes you rest on your own. Practice deep rest consciously.
Some people have to practice this in order to be equanimous and bring up more awareness in them. For some people it is by old impressions (samskaras) of some lives, past lives, births, it just happens. Sometimes right from the birth or sometimes at some particular period in life they start opening up. This is Samskara Sheshonya. Have you noticed this? Some people, after 30-40 years, suddenly open up to some spiritual experience. They have more awareness but unfortunately, most people are misguided. This is because there is no root of understanding of yoga. At that stage instead of being misled by such experiences, such evangelic experiences, they should know that they are all from samskjra shesha (old impressions). That is a different type of samadhi.
Bhavapratyayo videhaprakrutilayanam (Sutra 19) meaning that which is caused by this existence (i.e., you meditating in this level of existence) also influences those who do not have a body and those who have merged with nature. Samadhi is not the property of just this level of existence. It surpasses this level. It goes into the other worlds too. People who do not have a body, they too can get affected by meditation. When you meditate you are not just bringing a harmony within yourself, but you are influencing the subtle layers of the creation and the subtle bodies of all the different levels of existence in the creation. So your meditation influences those people who lived 100 years before you. Their consciousness and their mind are affected. And also it affects the minds /consciousness of people who would live in the future. This is because life is infinite. Though life is in every moment, it is also infinite. Your life has been here from thousands of years, from centuries and your life will continue to be here for centuries.
Videha means one who does not have a body. You can walk feeling as though you do not have a body and the mind is in such a state of equanimity. Those who do not have a body are also coming under the effect of yoga with Prakruti laya, which means completely submerged in the nature. They also attain the same stage of equanimity. Either you are so much away from material existence, completely not aware of the material world and the body or completely immersed in the object of the world. You can do it either with your eyes closed or looking and observing nature. This is Prakruti laya Samadhi - merging with the nature at that moment. Have you ever had this experience? No thoughts, no mind, no body, no awareness when you stare at nature? This is prakruti laya samadhi.
Prakruti Laya is very difficult but there are some people who practice it - sitting for hours together, in solitude, just observing till all thoughts disappear. All that they are left with is emptiness. You can do this as an experiment when you are worried. Just sit by a flowing river and keep looking at the water. Within a few minutes you feel as though a magnet is drawing you in. Your mind is being pulled in the direction of water flow. Knowing you are not the body but you just have a body is videha.