Distinguishing between a body that perishes and an eternal soul that cannot be measured.

The body will certainly come to an end, but the soul that possesses it is eternal, indestructible, and immeasurable. However, this does not mean that we should treat the body or life lightly.

Here, what is being corrected is the idea that equates physical death with the complete annihilation of the soul, and abandons one's duties solely based on this fear. While it may be impossible to avoid the destruction of the body, the soul itself does not perish. After pointing out this distinction, Krishna encourages Arjuna, who is on the battlefield, to "fight." This passage connects the teachings about the soul directly to his specific obligations.

Japanese Translation from the Geeta Press Edition - Chapter 2, Section 18: "The body will perish, therefore fight."

The subject that describes existing things in this way will explain what is "non-existent" in the following sentence.

Sanskrit original text

अन्तवन्त इमे देहा नित्यस्योक्ताः शरीरिणः ।
अनाशिनोऽप्रमेयस्य तस्माद्युध्यस्व भारत ॥ १८ ॥

Romanization

antavanta ime dehā nityasyoktāḥ śarīriṇaḥ |
anāśino 'prameyasya tasmād yudhyasva bhārata || 18 ||

All these bodies belong to the soul, which is immortal, indefinable, and eternal. It has been said that they are perishable. Therefore, Arjuna, fight. (18)

In the preceding sentence, the word "Dehāḥ," meaning "body," which is limited by "Ime," meaning "these," refers to all bodies. And in order to explain what "non-existent things" are, they are characterized as things that perish.

The intention is to show that the mind, sensations, and the gross or physical body – all of these are things that perish.

Just as a body and world belonging to a dream appear without any corresponding reality, so too do all these bodies appear as "real" due to ignorance, even though they are not real.

They do not have any "existing" existence. Therefore, their destruction is unavoidable. For that reason, it is futile to be sad about them.

The word Dehāḥ is used in the plural form, while the word Śarīriṇaḥ, which means "soul," is used in the singular form. This indicates that the subject implies that there is only one soul within all bodies.

For the ignorant, it appears that souls are different in each body. However, in reality, they are one. The word Śarīriṇaḥ refers to what was mentioned in the previous section as "something that exists." It is something that pervades the entire material world.

Furthermore, the three adjectives "eternal," "immortal," and "indefinable" are used to prove that it is identical to its "existing being."

Moreover, by calling it Śarīrī, meaning one who possesses a body, and demonstrating relationships with various bodies, the identity of the soul and god is shown.

The purpose is to demonstrate, in actual experience, that while different souls appear to be working within their respective bodies and maintaining those bodies, they are not actually separate.

They are one reality, a single principle of life and consciousness.

This can be understood through an analogy of a dream. Only the dreamer exists in a dream, and all observed diversity is merely part of the dream. And after waking up, only the dreamer remains. Similarly, the diversity seen in the world arises from ignorance. When knowledge appears like dawn, all diversity disappears.

By using the word "Tasmāt," which indicates a cause, and then ordering Arjuna to fight, the Lord is showing that: The body perishes, and its destruction is unavoidable. And the soul is eternal and cannot be destroyed. Since this has been proven, there was no reason for even a little sadness to remain.

Therefore, Arjuna should no longer show hesitation or reluctance about engaging in battle.