Now Sri Krishna gives some further description of soul.

BG 2.25

avyakto ‘yam acintyo ‘yam

avikaryo ‘yam ucyate

tasmad evam viditvainam

nanusocitum arhasi

SYNONYMS

avyaktah — invisible; ayam — this soul; acintyah — inconceivable; ayam — this soul; avikaryah — unchangeable; ayam — this soul; ucyate — is said; tasmat — therefore; evam — like this; viditva — knowing it well; enam — this soul; na — do not; anusocitum — to lament; arhasi — you deserve.

TRANSLATION

It is said that the soul is invisible, inconceivable and immutable. Knowing this, you should not grieve for the body.

avyakto ‘yam, is translated by Srila Prabhupada as the invisible nature or unmanifest aspect of the soul, which can’t be sensed, nor can it be perceived by our gross sensory faculties. acintyo ‘yam states that the soul is also inconceivable, if the soul is inconceivable, then how can we conceive it? Further, one might question, the need to understand the soul.

Unless, we think about soul, we cannot understand what life is ultimately meant for. Because life at the level of the body will soon be destroyed. Therefore, Srila Prabhupada states, acintyo ‘yam, means we cannot conceive soul by our own endeavors, we need scriptural guidance. There is limitation to our logical inferences which can’t fully conceive the entirety of the soul. So to get deeper understanding, one has to look at the scriptural tradition. Acintya doesn’t mean soul is entirely inconceivable, it simply means with our independent speculation we get some indication, but for a deeper understanding we need scripture.

Further, Srila Prabhupada refers to the six phases of change through which body undergoes viz. creation, growth, reproduction, preservation, deterioration and destruction. So these six changes are in connection with the body, not the soul—it does not under go changes avikaryo ‘yam ucyate. Underscoring the eternality of the soul and the ephimeral nature of the body, Krishna is empathically stating Arjuna, not to lament (tasmad evam viditvainam, nanusocitum arhasi).

Finding the connection between 25 (a,b) and 25 (c,d). So what is the connection between first part and the second part?

The first part outlines the characteristics of the soul, that it does not grow old, nor is it going to die (avikarya). It is always the same. Srila Prabhupada has explained this in the context of Arjuna’s apprehension about the death of Bhisma and Drona. But Krishna dispels this doubt by establishing the immortality of the soul. Although, anyone who dies will get a new body; either spiritual body (if they are liberated which will happen when they are dying in Sri Krishna’s presence) or they will get elevated bodies in the material universe based on their overall Karma. Thus, on a philosophical level there is no point of lamentation on the death of the physical body.