The devotees of the Lord do not bother about the impersonal Brahman conception of God; their faith and devotion bring them to surrender immediately unto the Supreme Lord, and out of the causeless mercy of Kṛṣṇa they can understand Kṛṣṇa. No one else can understand Him. So even great sages agree: What is ātmā, what is the Supreme? It is He whom we have to worship.
(Bhagavad-Gita----10:2----purport).

Realizing this, he becomes attached to the Supreme Personality of Godhead and surrenders to Him. At such a time one can understand that Lord Śrī Kṛṣṇa's mercy is everything, that He is the cause of all causes and that this material manifestation is not independent from Him. He realizes the material world to be a perverted reflection of spiritual variegatedness and realizes that in everything there is a relationship with the Supreme Lord Kṛṣṇa. Thus he thinks of everything in relation to Vāsudeva, or Śrī Kṛṣṇa. Such a universal vision of Vāsudeva precipitates one's full surrender to the Supreme Lord Śrī Kṛṣṇa as the highest goal. Such surrendered great souls are very rare.
(Bhagavad-Gita----7:19----purport).

As soon as the Kṛṣṇa sun is arisen within one's heart, the darkness of materialistic speculations about the Absolute Truth and the living beings is at once cleared off. In the presence of the sun, the darkness cannot stand, and the relative truths that were hidden within the dense darkness of ignorance become clearly manifested by the mercy of Kṛṣṇa, who is residing in everyone's heart as the Supersoul.
(Srimad Bhagavatam----1:2:21----purport).

When one wants to cross a large ocean, he requires a strong boat. It is said that this human form of life is a good boat by which one can cross the ocean of nescience. In the human form of life one can obtain the guidance of a good navigator, the spiritual master. One also gets a favorable wind by the mercy of Kṛṣṇa, and that wind is the instructions of Kṛṣṇa. The human body is the boat, the instructions of Lord Kṛṣṇa are the favorable winds, and the spiritual master is the navigator. The spiritual master knows well how to adjust the sails to catch the winds favorably and steer the boat to its destination. If, however, one does not take advantage of this opportunity, one wastes the human form of life. Wasting time and life in this way is the same as committing suicide.
(Srimad Bhagavatam----4:23:28----purport).

If one is fortunate enough to transcend all this so-called goodness and badness and come to the platform of devotional service by the mercy of Kṛṣṇa and the guru, his life becomes successful. In this regard, one must be very bold so that he can conquer these enemies of Kṛṣṇa consciousness. Not caring for the good and bad of this material world, one must boldly propagate Kṛṣṇa consciousness.
(Srimad Bhagavatam----7:15:43----purport).

Kṛṣṇa can become the director and spiritual master of anyone who is serious about getting the mercy of Kṛṣṇa. The Lord sends the spiritual master to train a devotee, and when the devotee is advanced, the Lord acts as the spiritual master within his heart.
(Srimad Bhagavatam----7:15:76----purport).

Kṛṣṇa and His name, fame, qualities and paraphernalia cannot be materially understood. Unless one is advanced in spiritual life (sevonmukhe hi jihvādau), one cannot see Kṛṣṇa. Therefore the ability to see Kṛṣṇa depends on Kṛṣṇa's mercy. The same privilege of being seen or unseen according to one's own desire was given to Mahārāja Nimi. Thus he lived in his original, spiritual body as an associate of the Supreme Personality of Godhead.
(Srimad Bhagavatam----9:13:11----purport).

Thus the transcendental causeless mercy of Lord Kṛṣṇa is manifested in the heart of the devotee. At such a time, material needs no longer exist. The lamentation that invariably accompanies material desires also vanishes. By the grace of the Lord one is elevated to the transcendental position, and then the transcendental mellows of the spiritual world are manifested in him. One's devotional service then becomes firm, and one engages in the Lord's transcendental loving service with great determination. All these combine to fully awaken the devotee's heart with love of Kṛṣṇa.
(Sri Caitanya Caritamrta----2:10:119----purport).

According to their karma, all living entities are wandering throughout the entire universe. Some of them are being elevated to the upper planetary systems, and some are going down into the lower planetary systems. Out of many millions of wandering living entities, one who is very fortunate gets an opportunity to associate with a bona fide spiritual master by the grace of Kṛṣṇa. By the mercy of both Kṛṣṇa and the spiritual master, such a person receives the seed of the creeper of devotional service.
(Sri Caitanya Caritamrta----2:19:151----purport).

Endowed with the mercy of the Supreme Personality of Godhead, the spiritual master distributes the mercy to those who are elevated and pious. Thus the spiritual master trains his disciples to render devotional service unto the Supreme Personality of Godhead. This is called guru-kṛpā. It is kṛṣṇa-prasāda, Kṛṣṇa's mercy, that He sends a bona fide spiritual master to the deserving disciple. By the mercy of Kṛṣṇa, one meets the bona fide spiritual master, and by the mercy of the spiritual master, the disciple is fully trained in the devotional service of the Lord.
(Sri Caitanya Caritamrta----2:19:152----purport).

As long as one labors under the bodily conception, he must fulfill volumes and volumes of material desires. Thus a person is called ātmārāma. When such an ātmārāma is favored by the mercy of Kṛṣṇa, he gives up his so-called self-satisfaction and engages in the transcendental loving service of the Lord.
(Sri Caitanya Caritamrta----2:24:218----translation).

According to the law of karma, everyone is destined to suffer or enjoy according to a certain material standard, but the mercy of Lord Kṛṣṇa is so powerful that the Lord can change all the reactions of one's past karma, or fruitive activities. Lord Śrī Caitanya Mahāprabhu specifically drew attention to the mercy of Lord Kṛṣṇa. That mercy is more powerful than anything else, for it had saved Raghunātha dāsa from the strong bondage of materialistic life, which the Lord compared to a hole where people pass stool. Śrī Caitanya Mahāprabhu gave His verdict that those addicted to the materialistic way of life are like worms that are living in stool but cannot give it up.
(Sri Caitanya Caritamrta----3:6:193----translation).

Sometimes, however, it is found that without undergoing any devotional process, one all of a sudden develops devotion for Lord Kṛṣṇa. This sudden development of the devotional attitude in a person must be understood as a special mercy of Kṛṣṇa or of His devotee. This apparently accidental development of ecstatic feelings through the causelessmercy of Kṛṣṇa can be divided into three groups: simply by speaking, simply by glancing and simply by good wishes.
(Nectar of Devotion).

If one can gradually advance his status in devotional service, this is understood to be due to the causeless mercy of Kṛṣṇa Himself. If a person is completely detached from material enjoyment and has developed pure ecstatic devotion, even if he is sometimes accidentally found not living up to the standard of devotional service, one should not be envious of him. It is confirmed also in Bhagavad-gītā that a devotee who has unflinching faith in and devotion to the Lord, even if sometimes found to be accidentally deviated from pure devotional characteristics, should still be counted among the pure. Unflinching faith in devotional service, in Lord Kṛṣṇa and in the spiritual master makes one highly elevated in the activities of devotional service.
(Nectar of Devotion).

When a devotee is never tired of executing devotional service and is always engaged in Kṛṣṇa conscious activities, constantly relishing the transcendental mellows in relationship with Kṛṣṇa, he is called perfect. This perfectional stage can be achieved in two ways: one may achieve this stage of perfection by gradual progress in devotional service, or one may become perfect by the causeless mercy of Kṛṣṇa, even though he has not executed all the details of devotional service.
(Nectar of Devotion).

The causeless mercy of Kṛṣṇa, the dust of His lotus feet, His prasāda and association with His devotees are some impetuses toward a devotee's engagement in transcendental loving service to the Lord.
(Nectar of Devotion).

It is said that this Age of Kali is three-fourths devoid of religious principles. Hardly one fourth of the principles of religion are still observed in this age. But by the mercy of Lord Kṛṣṇa, not only has this void of Kali-yuga been completely filled, but the religious process has been made so easy that simply by rendering transcendental loving service unto Lord Kṛṣṇa by chanting His holy names, Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare / Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare, one can achieve the highest result of religion, namely, being transferred to the highest planet within the spiritual world, Goloka Vṛndāvana. Considering all this, one can immediately appreciate the benefit of Lord Kṛṣṇa's appearance on the earth and understand that His giving relief to the people of the world by His appearance was not at all extraordinary.
(Krsna Book).