If you are actually serious to understand the transcendental science, spiritual knowledge, you must have guru

Expressions researched:
"If you are actually serious to understand the transcendental science, spiritual knowledge, oh, you must have guru"

Srimad-Bhagavatam Lectures

Tad-vijñānārtham is spiritual science. "Must approach." Gurum evābhigacchet samit-paniḥ śrotriyaṁ brahma-niṣṭham. Tasmād-guruṁ prapadyeta jijñāsuḥ śreya uttamam (SB 11.3.21). If you are actually serious to understand the transcendental science, spiritual knowledge, oh, you must have guru.

Lecture on SB 7.9.7 -- Mayapur, February 27, 1977:

Just like in our country, perhaps you know, there was a poet, Rabindranath Tagore. He got many distinction from the Oxford University. He got... He never went to school but he got the title "doctor," "Doctor Rabindranath Tagore." And if you think that "I shall also get doctorate without going to school," that is foolishness. That is special. Similarly, don't try to imitate. Follow the general course, sādhana-siddhi. The regulative principles you must follow as instructed in the śāstra. Therefore there are so many śāstras. And guru is guide. We must always... Even if you are nitya-siddha or kṛpa-siddha, you should not neglect the general regulative principle. That is very dangerous. Don't try to do that. We must follow. Nitya. Just like Caitanya Mahāprabhu. Caitanya Mahāprabhu is Kṛṣṇa Himself, God, but He is accepting guru. Who is His guru? He is guru of everyone, but He has also accepted Īśvara Purī as His guru. Kṛṣṇa Himself, He accepted His guru, Sāndīpani Muni, teaching us that without guru you cannot make any advance. Ādau gurvāśrayam. The first business is to accept guru. Tad-vijñānārthaṁ sa gurum evābhigacchet (MU 1.2.12). Don't think that "I am so advanced. I may not require any guru. I can do without guru." That is nonsense. That, not possible. "Must." Tad vijñānārtham. Tad-vijñānārtham is spiritual science. "Must approach." Gurum evābhigacchet samit-paniḥ śrotriyaṁ brahma-niṣṭham. Tasmād-guruṁ prapadyeta jijñāsuḥ śreya uttamam (SB 11.3.21). If you are actually serious to understand the transcendental science, spiritual knowledge, oh, you must have guru. Tasmād guruṁ prapadyeta jijñāsuḥ śreya uttamam. And... Just like Caitanya Mahāprabhu says, āmāra ājñāya guru hañā tāra' ei deśa (CC Madhya 7.128). Guru cannot be self-made. No. There is no such single instance throughout the whole Vedic literature. And nowadays, so many rascals, they are becoming guru without any authority. That is not guru. You must be authorized. Evaṁ paramparā-prāptam imaṁ rā... (BG 4.2). As soon as the paramparā is lost, sa kālena yoga naṣṭo parantapa, immediately finished. The spiritual potency finished. You can dress like a guru, you can talk big, big words, but it will never be effective.