“The realization of the personal form of the Lord is the highest perfectional stage of yoga. In the Sixth Chapter of Bhagavad-gita, where yoga practice is described, this realization of the personal form of the Lord is called the perfection of yoga. After practicing the sitting postures and other regulative principles of the system, one finally reaches the stage of samadhi–absorption in the Supreme. In the samadhi stage one can see the Supreme personality of Godhead in His partial form as Paramatma, or as He is. Samadhi is described in authoritative yoga scriptures, such as the Patanjali-sutras, to be a transcendental pleasure.
The yoga system described in the books of Patanjali is authoritative, and the modern so-called yogis who have manufactured their own ways, not consulting the authorities, are simply ludicrous. The Patanjali yoga system is called astanga-yoga. Sometimes impersonalists pollute the Patanjali yoga system because they are monists. Patanjali describes that the soul is transcendentally pleased when he meets the Supersoul and sees Him. If the existence of the Supersoul and the individual is admitted, then the impersonalist theory of monism is nullified. Therefore some impersonalists and void philosophers twist the Patanjali system in their own way and pollute the whole yoga process.
According to Patanjali, when one becomes free from all material desires he attains his real, transcendental situation, and realization of that stage is called spiritual power. In material activities a person engages in the modes of material nature. The aspirations of such people are (1) to be religious, (2) to be economically enriched, (3) to be able to gratify the senses and, at last, (4) to become one with the Supreme. According to the monists, when a yogi becomes one with the Supreme and loses his individual existence, he attains the highest stage, called kaivalya. But actually, the stage of realization of the Personality of Godhead is kaivalya. The oneness of understanding that the Supreme Lord is fully spiritual and that in full spiritual realization one can understand what He is–the Supreme Personality of Godhead– is called kaivalya, or, in the language of Patanjali, realization of spiritual power. His proposal is that when one is freed from material desires and fixed in spiritual realization of the self and the Superself, that is called cit-sakti. In full spiritual realization there is a perception of spiritual happiness, and that happiness is described in Bhagavad-gita as the supreme happiness, which is beyond the material senses. Trance is described to be of two kinds, samprajnata and asamprajnata, or mental speculation and self-realization. In samadhi or asamprajnata one can realize, by his spiritual senses, the spiritual form of the Lord. That is the ultimate goal of spiritual realization.
According to Patanjali, when one is fixed in constant realization of the supreme form of the Lord, one has attained the perfectional stage, as attained by Kardama Muni. Unless one attains this stage of perfection–beyond the perfection of the preliminaries of the yoga system–there is no ultimate realization. There are eight perfections in the astanga-yoga system. One who has attained them can become lighter than the lightest and greater than the greatest, and he can achieve whatever he likes. But even achieving such material success in yoga is not the perfection or the ultimate goal. The ultimate goal is described here: Kardama Muni saw the Supreme Personality of Godhead in His eternal form. Devotional service begins with the relationship of the individual soul and the Supreme Soul, or Kṛṣṇa and Kṛṣṇa’s devotees, and when one attains it there is no question of falling down. If, through the yoga system, one wants to attain the stage of seeing the Supreme Personality of Godhead face to face, but is attracted instead to attainment of some material power, then he is detoured from proceeding further. Material enjoyment, as encouraged by bogus yogis, has nothing to do with the transcendental realization of spiritual happiness. Real devotees of bhakti-yoga accept only the material necessities of life absolutely needed to maintain the body and soul together; they refrain completely from all exaggerated material sense gratification. They are prepared to undergo all kinds of tribulation, provided they can make progress in the realization of the Personality of Godhead.”
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Third Canto, Chapter 12 – Text 21