These aphorisms describe about siddhis including Aṣṭamā siddhis.

Yogis can read the mind of others; but one should have mastered jñāna yoga (the Yoga as based on the acquisition of true knowledge as opposed to the Yoga based on performance of ceremonial rites). Such a yogi develops powers to differentiate each person from others on specific qualities or external marks. By doing saṁyama on those qualities or marks, a jñāna yogi will be able to read others mind. Such a yogi can also fathom out his or her mind and transform that person.

With further reference to the previous aphorism, there are two types of saṁyama-s. One is to do saṁyama on the visible marks of a person. Second one is to do saṁyama on his thought processes (which unfolds in mind). By mastering these two saṁyama-s, Patañjali says that one can do wonders.

A jñāna yogi looks at an object by entirely focussing on it and while doing so, he will be able to segregate the object and its qualities. Similarly, this yogi can do the same type of saṁyama on his own self and disappear from others eyes. This is also known as antar-yoga or internal yoga.

Similarly, such a yogi can disconnect his other sensory organs and make them inactive. In the previous aphorism, eye was discussed and in this aphorism, other four sensory organs are referred. The procedure described in the previous aphorism is to be followed.

If a yogi does saṁyama on his karmas, he can know the date and time of his death. (It is also said that no human can know his karmas; going by this, it is difficult to understand how Patañjali has said this; no methods have been described to know one’s karma in this aphorism.)

If a yogi does saṁyama on friendship, compassion and other such qualities, the yogi will increase these qualities. He will have great compassion, useful friendship, etc.

{Now aṣṭamā siddhis are being explained. Saṁyama is focussing without minutest distraction. It is observing something with absolute attention. It is more to do with concentration of mind. We have to remember that only a yogi can literally practice these.}

All siddhis can be attained only through saṁyama. When we connect with an elephant, we get the strength of an elephant. Similarly, if saṁyama is done on a big rock, we become heavy like that rock. Similarly, if saṁyama is done on a bird’s feather, we become light and can fly in the sky.

Light is both within our body and also outside our body (such as sun). If saṁyama is done on the inner light, we can come to know of various actions happening miles away.

If saṁyama is done on the sun, one can know about the solar system.

If saṁyama is done on the moon, one can attain knowledge about stars.

If saṁyama is done on polar star (dhruva nakṣatra), one can know the movement of stars. Dhruva nakṣatra does not move and remains fixed in the North Pole.

If saṁyama is done on the navel chakra (maṇipūraka), one can see his inner body as seen in an x-ray.

If saṁyama is done on the throat chakra (viśuddhi), one can control appetite and thirst.

If saṁyama is done on kūrma nāḍi, one will not move during meditation, which is essential in entering into samādhi states.

If saṁyama is done on the light (this light is to be visualized) above sahasrāra, one can come into contact with siddhas. (This experience is also possible during quality meditation.)

If saṁyama is done on the heart chakra (anāhata), one attains mental purification. Further, one can understand his or her own mind and also minds of others.

Further Readings:

PATANJALI YOGA SUTRAS - 6

PATANJALI YOGA SUTRAS - 7