In the Bhagavad-gītā Kṛṣṇa says to Arjuna that, "I am speaking to you this science of Bhagavad-gītā." Imaṁ vivasvate yogaṁ proktavān aham avyayam (BG 4.1). Idaṁ yogam. Bhagavad-gītā means bhakti-yogam. So Kṛṣṇa said formerly, say, four hundred millions of years ago. Bhagavad-gītā is not new. It is . . . first of all it was spoken to sun-god, and from the Manu's age and others' age we can calculate it is about some millions of years ago it was spoken. Imaṁ vivasvate yogaṁ proktavān aham avyayam (BG 4.1). So Kṛṣṇa said: "That very old yoga system I am speaking to you again. It is not a new thing that I am manufacturing for you. No." Everything . . . God is eternal, and His instruction is also eternal. And the followers are also eternal. There is nothing new. Nityaḥ śāśvato 'yaṁ purāṇaḥ. Nityaḥ śāśvato 'yaṁ purāṇaḥ. Very old, but still, it is eternal and fresh. This is spiritual matter. You read Bhagavad-gītā. It was spoken four hundred millions of years ago, and then again, five thousand years ago. Still, if you read Bhagavad-gītā daily, you will find it fresh. You will never find it old. As Kṛṣṇa is never old, advaitam acyutam anādim ananta-rūpam ādyaṁ purāṇa-puruṣam (Bs. 5.33)—Kṛṣṇa is the purāṇa, the oldest man—but nava-yauvanaṁ ca. But He is always . . . see. You will find Kṛṣṇa just a young boy of twenty years. Nava-yauvanaṁ ca. So similarly, Kṛṣṇa's words, everything Kṛṣṇa, absolute. His name, His form, His quality, His activities—they are all fresh and new. Otherwise, how the devotees can glorify the same Kṛṣṇa daily with greater enthusiasm? Greater enthusiasm. The more you glorify, you'll feel more enthusiastic to more glorify, glorify, glorify.
This is spiritual. In the material world, if you speak one thing once, twice, thrice, four times, then it becomes disgusting. But how this Hare Kṛṣṇa mantra . . . you are chanting. You can chant twenty-four hours. It will feel fresh and enthusiasm. That is spiritual. Therefore . . . therefore it is not a subject matter . . . this sound is not like this radio, material sound. It is also sound, but it is spiritual sound, and it is coming from the spiritual world. Just like in the material world we can release some sound—from here, it can be heard from thousands of miles, but not more than that. The spiritual sound, it is released from many, many millions and millions and trillions of miles away, still it can be heard, provided you have got the machine to capture it. That is bhāgavata-prema.