A Kṛṣṇa conscious yogī is the perfect seer because he sees Kṛṣṇa, the Supreme, situated in everyone's heart as Supersoul (Paramātmā). Īśvaraḥ sarva-bhūtānāṁ hṛd-deśe 'rjuna tiṣṭhati. The Lord in His Paramātmā feature is situated within both the heart of the dog and that of a brāhmaṇa. The perfect yogī knows that the Lord is eternally transcendental and is not materially affected by His presence in either a dog or a brāhmaṇa. That is the supreme neutrality of the Lord. The individual soul is also situated in the individual heart, but he is not present in all hearts. That is the distinction between the individual soul and the Supersoul. One who is not factually in the practice of yoga cannot see so clearly. A Kṛṣṇa conscious person can see Kṛṣṇa in the heart of both the believer and the nonbeliever. In the smṛti this is confirmed as follows: ātatatvāc ca mātṛtvāc ca ātmā hi paramo hariḥ. The Lord, being the source of all beings, is like the mother and the maintainer. As the mother is neutral to all different kinds of children, the supreme father (or mother) is also. Consequently the Supersoul is always in every living being.
(Bhagavad-Gita----6:29----purport).

A yogī who is practicing meditation on the Supersoul sees within himself the plenary portion of Kṛṣṇa as Viṣṇu—with four hands, holding conchshell, wheel, club and lotus flower. The yogī should know that Viṣṇu is not different from Kṛṣṇa. Kṛṣṇa in this form of Supersoul is situated in everyone's heart. Furthermore, there is no difference between the innumerable Supersouls present in the innumerable hearts of living entities. Nor is there a difference between a Kṛṣṇa conscious person always engaged in the transcendental loving service of Kṛṣṇa and a perfect yogī engaged in meditation on the Supersoul. The yogī in Kṛṣṇa consciousness—even though he may be engaged in various activities while in material existence—remains always situated in Kṛṣṇa. This is confirmed in the Bhakti-rasāmṛta-sindhu (1.2.187) of Śrīla Rūpa Gosvāmī: nikhilāsv apy avasthāsu jīvan-muktaḥ sa ucyate. A devotee of the Lord, always acting in Kṛṣṇa consciousness, is automatically liberated.
(Bhagavad-Gita----6:31----purport).

Unlike the ordinary human being, Lord Kṛṣṇa clearly says that He completely knows what happened in the past, what is happening in the present, and what will happen in the future. In the Fourth Chapter we have seen that Lord Kṛṣṇa remembers instructing Vivasvān, the sun-god, millions of years ago. Kṛṣṇa knows every living entity because He is situated in every living being's heart as the Supersoul. But despite His presence in every living entity as Supersoul and His presence as the Supreme Personality of Godhead, the less intelligent, even if able to realize the impersonal Brahman, cannot realize Śrī Kṛṣṇa as the Supreme Person. Certainly the transcendental body of Śrī Kṛṣṇa is not perishable. He is just like the sun, and māyā is like a cloud. In the material world we can see that there is the sun and that there are clouds and different stars and planets.
(Bhagavad-Gita----7:26----purport).

One should directly approach Kṛṣṇa, for that will save time and energy. For example, if there is a possibility of going to the top of a building by the help of an elevator, why should one go by the staircase, step by step? Everything is resting on Kṛṣṇa's energy; therefore without Kṛṣṇa's shelter nothing can exist. Kṛṣṇa is the supreme ruler because everything belongs to Him and everything exists on His energy. Kṛṣṇa, being situated in everyone's heart, is the supreme witness. The residences, countries or planets on which we live are also Kṛṣṇa. Kṛṣṇa is the ultimate goal of shelter, and therefore one should take shelter of Kṛṣṇa either for protection or for annihilation of his distress. And whenever we have to take protection, we should know that our protection must be a living force. Kṛṣṇa is the supreme living entity.
(Bhagavad-Gita----9:18----purport).

The Lord is situated in everyone's heart as the Supersoul. Does this mean that He has become divided? No. Actually, He is one. The example is given of the sun: The sun, at the meridian, is situated in its place. But if one goes for five thousand miles in all directions and asks, "Where is the sun?" everyone will say that it is shining on his head. In the Vedic literature this example is given to show that although He is undivided, He is situated as if divided. Also it is said in Vedic literature that one Viṣṇu is present everywhere by His omnipotence, just as the sun appears in many places to many persons. And the Supreme Lord, although the maintainer of every living entity, devours everything at the time of annihilation. This was confirmed in the Eleventh Chapter when the Lord said that He had come to devour all the warriors assembled at Kurukṣetra.
(Bhagavad-Gita----13:17----purport).

He is situated in everyone's heart as the supreme controller. The Supreme has legs and hands distributed everywhere, and this cannot be said of the individual soul. Therefore that there are two knowers of the field of activity—the individual soul and the Supersoul—must be admitted. One's hands and legs are distributed locally, but Kṛṣṇa's hands and legs are distributed everywhere. This is confirmed in the Śvetāśvatara Upaniṣad (3.17): sarvasya prabhum īśānaṁ sarvasya śaraṇaṁ bṛhat. That Supreme Personality of Godhead, Supersoul, is the prabhu, or master, of all living entities; therefore He is the ultimate shelter of all living entities. So there is no denying the fact that the Supreme Supersoul and the individual soul are always different.
(Bhagavad-Gita----13:18----purport).

A living entity should therefore surrender unto the Supreme Personality of Godhead, who is situated in everyone's heart, and that will relieve him from all kinds of miseries of this material existence. By such surrender, not only will one be released from all miseries in this life, but at the end he will reach the Supreme God. The transcendental world is described in the Vedic literature (Ṛg Veda 1.22.20) as tad viṣṇoḥ paramaṁ padam. Since all of creation is the kingdom of God, everything material is actually spiritual, but paramaṁ padam specifically refers to the eternal abode, which is called the spiritual sky or Vaikuṇṭha.
(Bhagavad-Gita----18:62----purport).

The individual souls in the material world engage in different activities according to their past unfinished desires. After the dissolution of a particular body, the individual soul forgets everything, but the all-merciful Lord, who is situated in everyone's heart as the witness, the Supersoul, awakens him and reminds him of his past desires, and thus he begins to act accordingly in his next life. This unseen guidance is described as fate, and a sensible man can understand that this continues his material bondage in the three modes of nature.
(Srimad Bhagavatam----3:6:3----purport).

"Any person who is engaged one hundred percent in the transcendental loving service of the Lord, at His lotus feet, is very dear to the Personality of Godhead Hari, and the Lord, being situated in the heart of the devotee, excuses all kinds of sins committed by chance." It was never expected that a great personality like Brahmā would ever think of sex indulgence with his daughter. The example shown by Brahmā only suggests that the power of material nature is so strong that it can act upon everyone, even Brahmā. Brahmā was saved by the mercy of the Lord with a little punishment, but by the grace of the Lord he did not lose his prestige as the great Brahmā.
(Srimad Bhagavatam----3:12:34----purport).

One who engages in devotional service to the Lord according to regulative principles is automatically freed from material desires, and in that pure state of mind one can realize the Personality of Godhead. The Personality of Godhead, being situated in everyone's heart, instructs the devotee regarding pure devotional service so that he may ultimately achieve the association of the Lord.
(Srimad Bhagavatam----3:13:39----purport).

Every devotee wants to chant the transcendental qualities of the Lord. Devotees are always interested in hearing about the Lord's transcendental qualities, and they are always eager to glorify these qualities, but sometimes they feel inconvenienced by humbleness. The Personality of Godhead, being situated in everyone's heart, specifically gives a devotee intelligence to describe Him. It is therefore understood that when a devotee writes or speaks about the Supreme Personality of Godhead, his words are dictated by the Lord from within. This is confirmed in Bhagavad-gītā, Tenth Chapter: to those who constantly engage in the transcendental loving service of the Lord, the Lord, from within, dictates what to do next in order to serve Him.
(Srimad Bhagavatam----4:9:4----purport).

The Lord is always ready to give instructions to the pure devotee so that the devotee can advance further and further in devotional service. Since the Lord gives instructions as sarvātmā, the Supersoul, Lord Śiva offers Him respect with the words sarvasmā ātmane namaḥ. The individual soul is called ātmā, and the Lord is also called ātmā as well as Paramātmā. Being situated in everyone's heart, the Lord is known as the supreme ātmā. Therefore all obeisances are offered unto Him.
(Srimad Bhagavatam----4:24:33----purport).

The Supreme Personality of Godhead is situated in everyone's heart, and from Him issue a living entity's inclinations and disinclinations. This is confirmed in Bhagavad-gītā (15.15):
sarvasya cāhaṁ hṛdi sanniviṣṭo
mattaḥ smṛtir jñānam apohanaṁ ca
"I am seated in everyone's heart, and from Me come remembrance, knowledge and forgetfulness."
(Srimad Bhagavatam----4:24:41----purport).

"I am seated in everyone's heart, and from Me come remembrance, knowledge and forgetfulness." Thus the Lord as Paramātmā is situated in everyone's heart, and He gives directions to the living entity to act in whatever way the living entity desires. In this life and in his previous lives the living entity does not know that the Lord is giving him a chance to fulfill all kinds of desires. No one can fulfill any desire without the sanction of the Lord. All the facilities given by the Lord are unknown to the conditioned soul.
(Srimad Bhagavatam----4:25:10----purport).

Śrīla Rūpa Gosvāmī said that if he could somehow get millions of ears and tongues, then he could relish spiritual bliss by chanting the Hare Kṛṣṇa mahā-mantra. There is really nothing uninspiring for a highly advanced devotee. In Bhagavad-gītā the Lord says that He is situated in everyone's heart and that He helps the living entity forget and remember. By the grace of the Lord, the devotee gets inspiration.
(Srimad Bhagavatam----4:30:20----purport).

"The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy." The machine given by material nature—whether the machine of the body or the machine of the orbit, or kāla-cakra—works according to the orders given by the Supreme Personality of Godhead. The Supreme Personality of Godhead and material nature work together to maintain this great universe, and not only this universe but also the millions of other universes beyond this one.
(Srimad Bhagavatam----5:23:3----purport).

"The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy." The Supreme Lord gives the living entity a chance to enjoy in this material world as he desires, but He openly expresses His own desire that the living entity give up all material aspirations, fully surrender unto Him and return home, back to Godhead.
(Srimad Bhagavatam----6:16:9----purport).

The word ātmānam in this verse means paramātmānam. The Paramātmā, or Supersoul, is situated in the core of everyone's heart (antataḥ). This is confirmed in Bhagavad-gītā (18.61). Īśvaraḥ sarva-bhūtānāṁ hṛd-deśe 'rjuna tiṣṭhati. The īśvara, the Supreme Personality of Godhead, being situated in everyone's heart, gives directions to everyone in terms of one's capabilities in taking the instructions. The instructions of Bhagavad-gītā are open to everyone, but some people understand them properly, whereas others understand them so improperly that they cannot even believe in the existence of Kṛṣṇa, although reading Kṛṣṇa's book.
(Srimad Bhagavatam----7:1:9----purport).

"The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of material energy." A material body is manufactured by the external energy according to the direction of the Supreme Personality of Godhead. The conditioned soul, being seated on this machine, wanders throughout the universe, and because of his bodily conception of life he only suffers. Actually the suffering of being blasphemed and the enjoyment of being praised, the acceptance of a good welcome or of chastisement by harsh words, are felt in the material conception of life; but since the body of the Supreme Personality of Godhead is not material but sac-cid-ānanda-vigraha (Bs. 5.1), He is unaffected by insults or greetings, blasphemy or prayers.
(Srimad Bhagavatam----7:1:23----purport).

Such are the activities of Vaikuṇṭha. Since everyone is a servant, everyone is on the same platform and is allowed to serve the Lord according to his ability. As confirmed in Bhagavad-gītā (15.15), sarvasya cāhaṁ hṛdi sanniviṣṭo mattaḥ smṛtir jñānam apohanaṁ ca: the Lord is situated in everyone's heart, giving dictation according to the attitude of the servant. However, the Lord gives different dictation to the nondevotees and devotees. The nondevotees challenge the authority of the Supreme Lord, and therefore the Lord dictates in such a way that the nondevotees forget the Lord's service, life after life, and are punished by the laws of nature. But when a devotee very sincerely wants to render service to the Lord, the Lord dictates in a different way.
(Srimad Bhagavatam----7:5:12----purport).

The Lord is situated in everyone's heart, and as one desires, the Lord gives one various types of bodies, which are like machines. Riding on such a machine, the living entity wanders throughout the universe, under the control of material nature and its modes. Thus the living being is not at all free to act, but is fully under the control of material nature, which is fully under the control of the Supreme Personality of Godhead.
(Srimad Bhagavatam----7:13:30----purport).

To distribute prasāda to all living entities, the process is that we must first offer prasāda to the brāhmaṇas and the Vaiṣṇavas, for the demigods are represented by the brāhmaṇas. In this way the Supreme Personality of Godhead, who is situated in everyone's heart, will be worshiped. This is the Vedic system of offering prasāda. Whenever there is a ceremony for distribution of prasāda, the prasāda is offered first to the brāhmaṇas, then to the children and old men, then to the women, and then to animals like dogs and other domestic animals. When it is said that Nārāyaṇa, the Supreme Being, is situated in everyone's heart, this does not mean that everyone has become Nārāyaṇa or that a particular poor man has become Nārāyaṇa. Such a conclusion is rejected herein.
(Srimad Bhagavatam----7:14:18----purport).

"The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy." The living entity, who is part and parcel of the Supreme Personality of Godhead, exists on the mercy of the Lord, who is always with him in any form of body. The living entity desires a particular type of material enjoyment, and thus the Lord supplies him with a body, which is like a machine. Just to keep him alive in that body, the Lord remains with him as the puruṣa (Kṣīrodakaśāyī Viṣṇu).
(Srimad Bhagavatam----7:14:37----purport).

The Supreme Personality of Godhead, being situated in everyone's heart, and especially in the hearts of His devotees, is always ready to help devotees in adversity. Since He knows everything, He knows how things are to be adjusted, and He does the needful to relieve the suffering of His devotee.
(Srimad Bhagavatam----8:17:12----purport).

Unless one is situated in the transcendental loving service of the Lord, one is unable to understand the Supreme Personality of Godhead. The Lord is situated in everyone's heart. However, because the conditioned souls are influenced by material nature, they can see only the actions and reactions of material nature, but not the Supreme Personality of Godhead. One therefore must purify himself internally and externally.
(Srimad Bhagavatam----9:8:22----purport).

As far as the oṁkāra praṇava is concerned, it is considered to be the sound incarnation of the Supreme Personality of Godhead. As such, oṁkāra is eternal, unlimited, transcendental, supreme and indestructible. He (oṁkāra) is the beginning, middle and end, and He is beginningless as well. When one understands oṁkāra as such, he becomes immortal. One should thus know oṁkāra as a representation of the Supreme situated in everyone's heart. One who understands oṁkāra and Viṣṇu as being one and the same and all-pervading never laments in the material world, nor does he remain a śūdra. Although He (oṁkāra) has no material form, He is unlimitedly expanded, and He has unlimited form. By understanding oṁkāra one can become free from the duality of the material world and attain absolute knowledge. Therefore oṁkāra is the most auspicious representation of the Supreme Lord. Such is the description given by Māṇḍūkya Upaniṣad. One should not foolishly interpret an Upaniṣadic description and say that because the Supreme Personality of Godhead "cannot" appear Himself in this material world in His own form, He sends His sound representation(oṁkāra) instead. Due to such a false interpretation, oṁkāra comes to be considered something material, and consequently oṁkāra is misunderstood and praised as being simply an exhibition or symbol of the Lord. Actually oṁkāra is as good as any other incarnation of the Supreme Lord.
(Teachings of Lord Caitanya).

The Supreme Personality of Godhead is one without a second, and therefore He is all-powerful. He has inconceivable energies, of which three are principal. The devotee is considered to be one of these energies, never the energetic. The energetic is always the Supreme Lord. The energies are related to Him for the purpose of eternal service. A living entity in the conditioned stage can uncover his aptitude for serving the Absolute Truth by the grace of Kṛṣṇa and the spiritual master. Then the Lord reveals Himself within his heart, and he can know that Kṛṣṇa is seated in the heart of every pure devotee. Kṛṣṇa is actuallysituated in the heart of every living entity, but only a devotee can realize this fact.
(Sri Caitanya Caritamrta----1:1:61----purport).