Sankhya Yoga 2.25

 Verse 2.25

अव्यक्तोऽयमचिन्त्योऽयमविकार्योऽयमुच्यते |

तस्मादेवं विदित्वैनं नानुशोचितुमर्हसि || 25||

avyakto ’yam achintyo ’yam avikāryo ’yam uchyate

tasmādevaṁ viditvainaṁ nānuśhochitum arhasi

avyaktaḥ—unmanifested; ayam—this soul; achintyaḥ—inconceivable; ayam—this soul; avikāryaḥ—unchangeable; ayam—this soul; uchyate—is said; tasmāt—therefore; evam—thus; viditvā—having known; enam—this soul; na—not; anuśhochitum—to grieve; arhasi—befitting

Atma is spoken of as invisible, inconceivable, and unchangeable. Knowing this, you should not grieve for the body.

There is no reason to grieve

Vyaktham means that which is manifest and can be experienced by the sense organs. But atma is avyaktam, unmanifest and achinthya: inconceivable. Krishna says atma is not an object to be experienced by the sense organs or conceived by mind. Since it does not have limbs or specific properties, it is also called avikarya: the unchangeable. One can argue that atma is said to be sat, chit and ananda - atma is of the nature of existence, consciousness and limitlessness (some consider ananda means bliss which may not be wrong as well, since if something is limitless then it should be of the nature of bliss.), which could be considered either as parts of atma or its properties. Is it proper to say that atma is unchangeable or partless? Yes it is. Because existence, consciousness and limitlessness are not the properties but the very nature of atma. A property will have the quality of being present, absent or gradation in an object. An iron bar can be hot, cold or hotter. Here the iron bar is said to have the property of the temperature. But the nature of fire is heat. One can never separate heat from fire. In the same way, one can never separate the three from atma, for they are its very nature. 

One thinks that I am as good as the body, I am the doer, I am the enjoyer of the results of my actions, or I am happy at one time and am sad at another based on his wrong conclusions that I am the body, mind and senses. Based on these few verses taught by Krishna, one has to give up this wrong thinking and knows himself to be the sat-chit-ananda atma. Krishna tells Arjuna that there is no ground for you to grieve (anushochitum na arhasi). When you know that there is no death for atma, there is no ground for you to grieve about anything.

Krishna said that Arjuna need not grieve with regards to the death of Bhishma or Drona since atma has no death. But what if Arjuna is grieved about the destruction of their physical bodies? What if his grief is about the cessation of anatma? Krishna answers this question in the forthcoming verses.