Because it is the world of duality. There must be something dual, black-white, darkness-light, sukha, happiness-distress, father-son. There must be. This is called relative world

Expressions researched:
"Because it is the world of duality. There must be something dual: black-white, darkness-light, sukha, happiness, distress, father-son. There must be. This is called relative world"

Bhagavad-gita As It Is Lectures

Because it is the world of duality. There must be something dual, black-white, darkness-light, sukha, happiness-distress, father-son. There must be. This is called relative world. One thing, if you understand one thing, you must know the other thing, opposite. Otherwise, it has no meaning. In the absolute world, there is no such thing, opposite elements.

Lecture on BG 2.36-37 -- London, September 4, 1973:

Prabhupāda: So Kṛṣṇa says in two ways that, "If you don't fight, then your enemies will blaspheme you." Avācya-vādāṁś ca vadiṣyanti bahūn. "They'll concoct, manufacture some blasphemy against you. You are becoming very much sorry to fight with your kinsmen. Undoubtedly you are very sorry. But if you are blasphemed, defamed by your enemies, better, before getting that, you better die in the fight. And dying, by dying, you are not loser. Because hato vā prāpsyasi svargam. Even if you die, don't think that you are loser, because immediately you are promoted to the heavenly planet. Because you are fighting for the right cause, it becomes puṇyavān," puṇyavān, righteous. The heavenly planet is meant for righteous persons. "So by dying, by your death in this righteous fighting, you'll be promoted to the heavenly planet. So both ways you will be profited." Hato vā prāpsyasi svargam and jitvā vā bhokṣyase mahīm. "And if you become victorious, then you enjoy the kingdom. So both ways you are profited. There is no loss on your part." Tasmāt, "Therefore," uttiṣṭha kaunteya yuddhāya kṛta niścayaḥ, kṛta niścayaḥ, "definitely decide it that 'I must fight. Fighting must be there,' " yuddhāya, for matter of fighting. Uttiṣṭha, "Get up. Why are you sitting like coward?" Encouraging.

hato vā prāpsyasi svargaṁ

jitvā vā bhokṣyase mahīm

tasmād uttiṣṭha kaunteya

yuddhāya kṛta niścayaḥ

(BG 2.37)

That's all right. We can read another verse. There is little time.

Pradyumna:

sukha-duḥkhe same kṛtvā

lābhālābhau jayājayau

tato yuddhāya yujyasva

naivaṁ pāpam avāpsyasi

(BG 2.38)

(break)

Prabhupāda:

sukha-duḥkhe same kṛtvā

lābhālābhau jayājayau

tato yuddhāya yujyasva

naivaṁ pāpam avāpsyasi

(BG 2.38)

Here, in this material world, when you work, there are two things: either loss or gain. Either happiness or distress, sukha-duḥkha. Loss or gain, victory or . . . what is called, the opposite?

Devotees: Defeat.

Prabhupāda: Defeat. Because it is the world of duality. There must be something dual: black-white, darkness-light, sukha, happiness, distress, father-son. There must be. This is called relative world. One thing, if you understand one thing, you must know the other thing, opposite. Otherwise, it has no meaning. In the absolute world there is no such thing, opposite elements. So here, Kṛṣṇa is suggesting about the absolute duty, lābhālābhau. When there is loss or gain, you are the same. Generally, when there is gain, we are very jubilant, and when there is loss, we become morose. But here, Kṛṣṇa is teaching that, "You remain in one position, either it is loss or gain, either it is victory or defeat, either it is happiness or distress." This is brahma-bhūta.

Brahma-bhūtaḥ prasannātmā na śocati na kāṅkṣati (BG 18.54). A devotee is always prasannātmā, because his happiness is to serve Kṛṣṇa. His only business is to see Kṛṣṇa happy, that's all. This is devotion. There may be loss or gain, there may be victory or defeat, there may be distress or happiness, it doesn't matter. He's not affected with this duality. That is being taught now. Real Bhagavad-gītā begins here. Kṛṣṇa is teaching. In the last also . . . this will go on in different languages up to the end of the Bhagavad-gītā. Mām ekaṁ śaraṇaṁ vraja (BG 18.66). That's all. Saṁsiddhir hari-toṣaṇam (SB 1.2.13). Bhāgavata also confirms this. You do not look after whether it is loss or gain, but you have to see whether Kṛṣṇa is satisfied. That's all. That is your only business. That is your only business.