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. The Lord says that Brahmā may take the answers as He explains them. This means that transcendental knowledge of the absolute Supreme Being can be known if it is made known by the Lord Himself. By the mental speculation of the greatest mundane thinkers, the Absolute Truth cannot be understood. The mental speculators can reach up to the standard of impersonal Brahman realization, but, factually, complete knowledge of transcendence is beyond the knowledge of impersonal Brahman.
(Srimad Bhagavatam-----2:9:31-----purport).

Now this lifting of the Govardhana Hill by a seven-year-old boy may be unbelievable for the faithless, but for the devotees it is absolutely believable. The devotee believes in the almighty potency of the Lord, while the faithless say that the Lord is almighty but do not believe it. Such men with a poor fund of knowledge do not know that the Lord is the Lord eternally and that one cannot become the Lord by meditation for millions of years or by mental speculation for billions of years.
(Srimad Bhagavatam-----2:9:32-----purport).

The sun reveals itself. Therefore the action of different energies of the Lord, or the Personality of Godhead Himself, can be realized by the light manifested by the causeless mercy of the Lord. The impersonalists say that God cannot be seen. God can be seen by the light of God and not by man-made speculations. Here this light is specifically mentioned as vidyāt, which is an order by the Lord to Brahmā. This direct order of the Lord is a manifestation of His internal energy, and this particular energy is the means of seeing the Lord face to face. Not only Brahmā but anyone who may be graced by the Lord to see such merciful direct internal energy can also realize the Personality of Godhead without any mental speculation.
(Srimad Bhagavatam-----2:9:34-----purport).

One who has unflinching devotion unto the Supreme Personality of Godhead must have all the good qualities of the demigods, and contrarily one who is not a devotee of the Lord must be hovering in the darkness of mental speculation and thus must be engaged in material impermanence. Śrīmad-Bhāgavatam (11.11.18) says:
śabda-brahmaṇi niṣṇāto
na niṣṇāyāt pare yadi
śramas tasya śrama-phalo
hy adhenum iva rakṣataḥ
"One may be well versed in all the transcendental literature of the Vedas, but if he fails to be acquainted with the Supreme, then it must be concluded that all of his education is like the burden of a beast or like one's keeping a cow without milking capacity."
(Srimad Bhagavatam-----2:9:36-----purport).

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).

In the Vedas it is said that the Supreme Lord or the Paramātmā cannot be understood simply by the strength of one's erudition or power of mental speculation: nāyam ātmā pravacanena labhyo na medhayā na bahunā śrutena (Kaṭha Upaniṣad 1.2.23). He can be known only by one who has the mercy of the Lord. The Yādavas were all exceptionally learned and experienced, but in spite of their knowing the Lord as the one who lives in everyone's heart, they could not understand that He is the original Personality of Godhead.
(Srimad Bhagavatam-----3:2:9-----purport).

It is a fact that persons who are trying to understand the Supreme Truth by their personal endeavors of mental speculation or mystic powers of yoga achieve the same goal as others who are personally killed by the Lord. Both achieve the salvation of merging in the brahma-jyotir rays of the transcendental body of the Lord. The Lord was merciful even to His enemy, and the success of the King of Cedi was observed by everyone who was present in the assembly. Vidura was also present there, and therefore Uddhava referred the incident to his memory.
(Srimad Bhagavatam-----3:2:19-----purport).

According to this class of men, who are situated in pure devotional service to the Lord, the highest goal of human life is puruṣārtha, devotional service to the Lord, the real mission of life. The impersonalists, because they engage in mental speculation and have no faith in the Personality of Godhead, have no business hearing the topics of Kṛṣṇa. Such persons are pitiable for the first-class pure devotees of the Lord. The pitiable impersonalists pity those who are influenced by the modes of ignorance and passion, but the pure devotees of the Lord take pity on them both because both waste their most valuable time in the human form of life in false pursuits, sense enjoyment and mental speculative presentations of different theories and goals of life.
(Srimad Bhagavatam-----3:5:14-----purport).

There are many topics for different persons in different modes of material nature, but the essential topics are those in relationship with the Supreme Lord. Unfortunately, materially affected conditioned souls are all more or less averse to topics of the Supreme Lord because some of them do not believe in the existence of God and some of them believe only in the impersonal feature of the Lord. In both cases there is nothing for them to say of God. Both the nonbelievers and the impersonalists deny the essence of all topics; therefore, they engage in topics of relativity in various ways, either in sense gratification or in mental speculation. For the pure devotees like Vidura, the topics of both the mundaners and the mental speculators are useless in all respects. Thus Vidura requested Maitreya to talk of the essence only, the talks of Kṛṣṇa, and nothing else.
(Srimad Bhagavatam-----3:5:15-----purport).

Mahat-tattva, or the great causal truth, transforms into false ego, which is manifested in three phases—cause, effect and the doer. All such activities are on the mental plane and are based on the material elements, gross senses and mental speculation. The false ego is represented in three different modes—goodness, passion and ignorance.
A pure living entity in his original spiritual existence is fully conscious of his constitutional position as an eternal servitor of the Lord. All souls who are situated in such pure consciousness are liberated, and therefore they eternally live in bliss and knowledge in the various Vaikuṇṭha planets in the spiritual sky. When the material creation is manifested, it is not meant for them. The eternally liberated souls are called nitya-muktas, and they have nothing to do with the material creation. The material creation is meant for rebellious souls who are not prepared to accept subordination under the Supreme Lord. This spirit of false lordship is called false ego. It is manifested in three modes of material nature, and it exists in mental speculation only.

(Srimad Bhagavatam-----3:5:29-----translation and purport).