Lord Brahmā is the topmost devotee of the Lord within the universe, and therefore the Personality of Godhead replied to his four principal inquiries in four important statements, which are known as the original Bhāgavatam in four verses. These were Brahmā's questions: (1) What are the forms of the Lord both in matter and in transcendence? (2) How are the different energies of the Lord working? (3) How does the Lord play with His different energies? (4) How may Brahmā be instructed to discharge the duty entrusted to Him? The prelude to the answers is this verse under discussion, wherein the Lord informs Brahmā that knowledge of Him, the Supreme Absolute Truth, as it is stated in the revealed scriptures, is very subtle and cannot be understood unless one is self-realized by the grace of the Lord.
(SRIMAD BHAGAVATAM------2:9:31-------PURPORT).

As in the Bhagavad-gītā, Tenth Chapter, the Personality of Godhead, Lord Kṛṣṇa, has summarized the whole text in four verses, namely, ahaṁ sarvasya prabhavaḥ (B.G.10:8), etc., so the complete Śrīmad-Bhāgavatam has also been summarized in four verses, as aham evāsam evāgre, etc. Thus the secret purpose of the most important Bhāgavatite conclusion has been explained by the original speaker of the Śrīmad-Bhāgavatam, who was also the original speaker of the Bhagavad-gītā, the Personality of Godhead, Lord Śrī Kṛṣṇa. There are many grammarians and nondevotee material wranglers who have tried to present false interpretations of these four verses of the Śrīmad-Bhāgavatam but the Lord Himself advised Brahmājī not to be deviated from the fixed conclusion the Lord had taught him. The Lord was the teacher of the nucleus of Śrīmad-Bhāgavatam in four verses, and Brahmā was the receiver of the knowledge. Misinterpretation of the word aham by the word jugglery of the impersonalist should not disturb the mind of the strict followers of the Śrīmad-Bhāgavatam. Śrīmad-Bhāgavatam is the text of the Personality of Godhead and His unalloyed devotees, who are also known as the bhāgavatas, and any outsider should have no access to this confidential literature of devotional service.
(SRIMAD BHAGAVATAM------2:9:37-------PURPORT).

Because Brahmā qualified himself for such reception, the Lord was pleased to disclose the purpose of Śrīmad-Bhāgavatam. This direct instruction by the Lord to any devotee who is detached from the world of sense gratification is possible, as stated in the Bhagavad-gītā (B.G.10:10):
teṣāṁ satata-yuktānāṁ
bhajatāṁ prīti-pūrvakam
dadāmi buddhi-yogaṁ taṁ
yena mām upayānti te
Unto the devotees who are constantly engaged in the Lord's transcendental loving service (prīti-pūrvakam), the Lord, out of His causeless mercy upon the devotee, gives direct instructions so that the devotee may make accurate progress on the path returning home, back to Godhead. One should not, therefore, try to understand these four verses of Śrīmad-Bhāgavatam by mental speculation. Rather, by direct perception of the Supreme Personality of Godhead, one is able to know all about His abode, Vaikuṇṭha, as was seen and experienced by Brahmājī. Such Vaikuṇṭha realization is possible by any devotee of the Lord situated in the transcendental position as a result of devotional service.

(SRIMAD BHAGAVATAM------2:9:37-------PURPORT).

Although the Śrīmad-Bhāgavatam was spoken in four verses, it had ten characteristics, which will be explained in the next chapter. In the four verses it is first said that the Lord existed before the creation, and thus the beginning of the Śrīmad-Bhāgavatam includes the Vedānta aphorism janmādy asya (S.B.1:1:1). Janmādy asya is the beginning, yet the four verses in which it is said that the Lord is the root of everything that be, beginning from the creation up to the supreme abode of the Lord, naturally explain the ten characteristics. One should not misunderstand by wrong interpretations that the Lord spoke only four verses and that therefore all the rest of the 17,994 verses are useless. The ten characteristics, as will be explained in the next chapter, require so many verses just to explain them properly. Brahmājī had also advised Nārada previously that he should expand the idea he had heard from Brahmājī. Śrī Caitanya Mahāprabhu instructed this to Śrīla Rūpa Gosvāmī in a nutshell, but the disciple Rūpa Gosvāmī expanded this very elaborately, and the same subject was further expanded by Jīva Gosvāmī and even further by Śrī Viśvanātha Cakravartī Ṭhākura. We are just trying to follow in the footsteps of all these authorities. So Śrīmad-Bhāgavatam is not like ordinary fiction or mundane literature. It is unlimited in strength, and however one may expand it according to one's own ability, Bhāgavatam still cannot be finished by such expansion. Śrīmad-Bhāgavatam, being the sound representation of the Lord, is simultaneously explained in four verses and in four billion verses all the same, inasmuch as the Lord is smaller than the atom and bigger than the unlimited sky. Such is the potency of Śrīmad-Bhāgavatam.

(SRIMAD BHAGAVATAM------2:9:44-------PURPORT).

In the Catuḥ-ślokī of Śrīmad-Bhāgavatam, the Lord says, aham evāsam evāgre: "I was existing in the beginning before the creation." (S.B.2:9:33) In the Vedas it is also said, eko nārāyaṇa āsīt: "Before the creation there was only Nārāyaṇa." This is also confirmed by Śaṅkarācārya. Nārāyaṇaḥ paro 'vyaktāt: "Nārāyaṇa is transcendental to the creation." (Gīta-bhāṣya) Since all the activities of Nārāyaṇa are spiritual, when Nārāyaṇa said, "Let there be creation," that creation was all-spiritual. The "material" only exists for those who have forgotten that Nārāyaṇa is the original cause.
(SRIMAD BHAGAVATAM------2:24:64-------PURPORT).