The rituals and sacrifices mentioned in the karma-kāṇḍa division of the Vedic literature are meant to encourage gradual development of self-realization. And the purpose of self-realization is clearly stated in the Fifteenth Chapter of the Bhagavad-gītā (15.15): the purpose of studying the Vedas is to know Lord Kṛṣṇa, the primeval cause of everything. So, self-realization means understanding Kṛṣṇa and one's eternal relationship with Him. The relationship of the living entities with Kṛṣṇa is also mentioned in the Fifteenth Chapter of Bhagavad-gītā (15.7). The living entities are parts and parcels of Kṛṣṇa; therefore, revival of Kṛṣṇa consciousness by the individual living entity is the highest perfectional stage of Vedic knowledge.
(Bhagavad-Gita----2:46----purport).

Lust is only the perverted reflection of the love of God which is natural for every living entity. But if one is educated in Kṛṣṇa consciousness from the very beginning, that natural love of God cannot deteriorate into lust. When love of God deteriorates into lust, it is very difficult to return to the normal condition. Nonetheless, Kṛṣṇa consciousness is so powerful that even a late beginner can become a lover of God by following the regulative principles of devotional service. So, from any stage of life, or from the time of understanding its urgency, one can begin regulating the senses in Kṛṣṇa consciousness, devotional service of the Lord, and turn the lust into love of Godhead—the highest perfectional stage of human life.
(Bhagavad-Gita----3:41----purport).

One has to understand this fact with conviction, although it is incomprehensible to mundane scholars and empiric philosophers. As stated in the Vedas (Puruṣa-bodhinī Upaniṣad):
eko devo nitya-līlānurakto
bhakta-vyāpī hṛdy antar-ātmā
"The one Supreme Personality of Godhead is eternally engaged in many, many transcendental forms in relationships with His unalloyed devotees." This Vedic version is confirmed in this verse of the Gītā personally by the Lord. He who accepts this truth on the strength of the authority of the Vedas and of the Supreme Personality of Godhead and who does not waste time in philosophical speculations attains the highest perfectional stage of liberation. Simply by accepting this truth on faith, one can, without a doubt, attain liberation. The Vedic version tat tvam asi is actually applied in this case. Anyone who understands Lord Kṛṣṇa to be the Supreme, or who says unto the Lord "You are the same Supreme Brahman, the Personality of Godhead," is certainly liberated instantly, and consequently his entrance into the transcendental association of the Lord is guaranteed.
(Bhagavad-Gita----4:9----purport).

"By execution of devotional service under the guidance of the spiritual master, one becomes free from all material attachment, attains steadiness in self-realization, and acquires a taste for hearing about the Absolute Personality of Godhead, Śrī Kṛṣṇa. This taste leads one further forward to attachment for Kṛṣṇa consciousness, which is matured in bhāva, or the preliminary stage of transcendental love of God. Real love for God is called prema, the highest perfectional stage of life." In the prema stage there is constant engagement in the transcendental loving service of the Lord. So, by the slow process of devotional service, under the guidance of the bona fide spiritual master, one can attain the highest stage, being freed from all material attachment, from the fearfulness of one's individual spiritual personality, and from the frustrations that result in void philosophy. Then one can ultimately attain to the abode of the Supreme Lord.
(Bhagavad-Gita----4:10----purport).

When one searches for a devotee and fortunately gets a devotee's association one actually begins to study and understand Bhagavad-gītā. By advancement in the association of the devotee one is placed in devotional service, and this service dispels all one's misgivings about Kṛṣṇa, or God, and Kṛṣṇa's activities, form, pastimes, name and other features. After these misgivings have been perfectly cleared away, one becomes fixed in one's study. Then one relishes the study of Bhagavad-gītā and attains the state of feeling always Kṛṣṇa conscious. In the advanced stage, one falls completely in love with Kṛṣṇa. This highest perfectional stage of life enables the devotee to be transferred to Kṛṣṇa's abode in the spiritual sky, Goloka Vṛndāvana, where the devotee becomes eternally happy.
(Bhagavad-Gita----8:28----purport).

When a person knows the goal of life but is addicted to the fruits of activities, he is acting in karma-yoga. When he knows that the goal is Kṛṣṇa but he takes pleasure in mental speculations to understand Kṛṣṇa, he is acting in jñāna-yoga. And when he knows the goal and seeks Kṛṣṇa completely in Kṛṣṇa consciousness and devotional service, he is acting in bhakti-yoga, or buddhi-yoga, which is the complete yoga. This complete yoga is the highest perfectional stage of life.
(Bhagavad-Gita----10:10----purport).

In the human form of life, a living entity is expected to be sane and to follow the regulations given for elevating his life to the highest platform, but if he does not follow them, then he degrades himself. But even if he follows the rules and regulations and moral principles and ultimately does not come to the stage of understanding the Supreme Lord, then all his knowledge becomes spoiled. And even if he accepts the existence of God, if he does not engage himself in the service of the Lord his attempts are spoiled. Therefore one should gradually raise himself to the platform of Kṛṣṇa consciousness and devotional service; it is then and there that he can attain the highest perfectional stage, not otherwise.
(Bhagavad-Gita----16:23----purport).

The highest stage of perfection is possible for everyone to attain this stage by practice of devotional service.
(Srimad Bhagavatam----1:9:43----purport).

Attainment of this stage of pure spiritual life is the highest perfection, and this stage is called svarūpa, or the factual identity of the living being.
(Srimad Bhagavatam----1:10:28----purport).

The simple method of hearing from the right source, Śrīmad-Bhāgavatam, will lead one to the highest perfectional stage of yoga.
(Srimad Bhagavatam----2:7:10----purport).

Bhakti-yoga begins if a person has the firm conviction that simply discharging devotional service to the Lord in full transcendental love can elevate him to the highest perfectional stage of life.
(Srimad Bhagavatam----2:9:18----purport).

The Lord says that the highest perfectional stage of learning is to know Him and His abode, devoid of all illusion.
(Srimad Bhagavatam----2:9:22----purport).

The glories of the Lord must be always and everywhere proclaimed. One should hear about His glories, one should chant about His glories, and one should always remember His glories because that is the highest perfectional stage of life.
(Srimad Bhagavatam----2:9:36----purport).

If one seriously engages in Kṛṣṇa consciousness, that is the highest perfectional stage.
(Srimad Bhagavatam----3:25:44----purport).