Pṛthu Mahārāja desired to serve the Lord with the goddess of fortune, but this desire does not mean that he was situated on the platform of mādhurya-rasa. The goddess of fortune is engaged in the service of the Lord in the rasa of mādhurya, conjugal love. Although her position is on the chest of the Lord, the goddess of fortune, in her position as a devotee, takes pleasure in serving the lotus feet of the Lord. Pṛthu Mahārāja was thinking only of the lotus feet of the Lord because he is on the platform of dāsya-rasa, or servitorship of the Lord. From the next verse we learn that Pṛthu Mahārāja was thinking of the goddess of fortune as the universal mother, jagan-mātā. Consequently there was no question of his competing with her on the platform of mādhurya-rasa.
(Srimad Bhagavatam------4:20:27-------purport).

Beyond the planetary systems in the material sky, there is another sky, which is known as paravyoma, or the spiritual sky, where there are spiritual planets. The inhabitants of those planets engage in varieties of loving service unto the Supreme Personality of Godhead, which include different rasas, or relationships, known as dāsya-rasa, sakhya-rasa, vātsalya-rasa, mādhurya-rasa and, above all, parakīya-rasa. This parakīya-rasa, or paramour love, is prevalent in Kṛṣṇaloka, where Lord Kṛṣṇa lives. This planet is also called Goloka Vṛndāvana, and although Lord Kṛṣṇa lives there perpetually, He also expands Himself in millions and trillions of forms. In one of such forms He appears on this material planet in a particular place known as Vṛndāvana-dhāma, where He displays His original pastimes of Goloka Vṛndāvana-dhāma in the spiritual sky in order to attract the conditioned souls back home, back to Godhead.
(Srimad Bhagavatam------4:20:35-36-------purport).

There are many devotees in rāga-mārga, which is exhibited in Vṛndāvana. Whether in dāsya-rasa, sakhya-rasa, vātsalya-rasa or mādhurya-rasa, all the devotees of Kṛṣṇa are always overwhelmed by thoughts of Kṛṣṇa. When Kṛṣṇa is away from Vṛndāvana tending the cows in the forest, the gopīs, in the mādhurya-rasa, are always absorbed in thoughts of how Kṛṣṇa walks in the forest. The soles of His feet are so soft that the gopīs would not dare keep His lotus feet on their soft breasts. Indeed, they consider their breasts a very hard place for the lotus feet of Kṛṣṇa, yet those lotus feet wander in the forest, which is full of thorny plants. The gopīs are absorbed in such thoughts at home, although Kṛṣṇa is away from them.
(Srimad Bhagavatam------7:1:27-------purport).

The essential point in this connection is that one should be fully absorbed in thoughts of Kṛṣṇa, twenty-four hours a day. There are many devotees in rāga-mārga, which is exhibited in Vṛndāvana. Whether in dāsya-rasa, sakhya-rasa, vātsalya-rasa or mādhurya-rasa, all the devotees of Kṛṣṇa are always overwhelmed by thoughts of Kṛṣṇa. When Kṛṣṇa is away from Vṛndāvana tending the cows in the forest, the gopīs, in the mādhurya-rasa, are always absorbed in thoughts of how Kṛṣṇa walks in the forest. The soles of His feet are so soft that the gopīs would not dare keep His lotus feet on their soft breasts. Indeed, they consider their breasts a very hard place for the lotus feet of Kṛṣṇa, yet those lotus feet wander in the forest, which is full of thorny plants. The gopīs are absorbed in such thoughts at home, although Kṛṣṇa is away from them.
(Srimad Bhagavatam------7:1:27-------purport).

The bhāva stage is the final division before one reaches love of Godhead. The word sarva-bhāva means that one can love the Supreme Personality of Godhead in different transcendental modes of mellows, beginning with dāsya, sakhya, vātsalya and mādhurya. In the śānta stage, one is on the border of loving service to the Lord. Pure love of Godhead begins from dāsya and develops to sakhya, vātsalya and then mādhurya. Still, in any of these five mellows one can render loving service to the Supreme Lord. Since our main business is to love the Supreme Personality of Godhead, one can render service from any of the above-mentioned platforms of love.
(Srimad Bhagavatam------7:9:54-------purport).

After His appearance, Lord Kṛṣṇa thought that He had not distributed the transcendental personal dealings with His devotees in dāsya, sakhya, vātsalya and mādhurya. One may understand the science of the Supreme Personality of Godhead from the Vedic literatures and thus become a devotee of the Lord and worship Him within the regulative principles described in the scriptures, but one will not know in this way how Kṛṣṇa is served by the residents of Vrajabhūmi. One cannot understand the dealings of the Lord in Vṛndāvana simply by executing the ritualistic regulative principles mentioned in the scriptures. By following scriptural injunctions one may enhance his appreciation for the glories of the Lord, but there is no chance for one to enter into personal dealings with Him. Giving too much attention to understanding the exalted glories of the Lord reduces the chance of one's entering into personal loving affairs with the Lord. To teach the principles of such loving dealings, the Lord decided to appear as Lord Caitanya.
(Sri Caitanya Caritamrta------1:3:16-------purport).

Of the four kinds of reciprocation of loving service—dāsya, sakhya, vātsalya and mādhurya—mādhurya is considered the fullest. But the conjugal relationship is further divided into two varieties, namely svakīya and parakīya. Svakīya is the relationship with Kṛṣṇa as a formally married husband, and parakīya is the relationship with Kṛṣṇa as a paramour. Expert analysts have decided that the transcendental ecstasy of the parakīya mellow is better because it is more enthusiastic. This phase of conjugal love is found in those who have surrendered to the Lord in intense love, knowing well that such illicit love with a paramour is not morally approved in society. The risks involved in such love of Godhead make this emotion superior to the relationship in which such risk is not involved. The validity of such risk, however, is possible only in the transcendental realm. Svakīya and parakīya conjugal love of Godhead have no existence in the material world, and parakīya is not exhibited anywhere in Vaikuṇṭha, but only in the portion of Goloka Vṛndāvana known as Vraja.
Some devotees think that Kṛṣṇa is eternally the enjoyer in Goloka Vṛndāvana but only sometimes comes to the platform of Vraja to enjoy parakīya-rasa. The six Gosvāmīs of Vṛndāvana, however, have explained that Kṛṣṇa's pastimes in Vraja are eternal, like His other activities in Goloka Vṛndāvana. Vraja is a confidential part of Goloka Vṛndāvana. Kṛṣṇa exhibited His Vraja pastimes on the surface of this world, and similar pastimes are eternally exhibited in Vraja in Goloka Vṛndāvana, where parakīya-rasa is ever existent.
(Sri Caitanya Caritamrta------1:4:50-------purport).

Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura comments in his Anubhāṣya that among the five tattvas, two are energies (śakti-tattva) and the three others are energetic (śaktimān tattva). Unalloyed and internal devotees are both engaged in the favorable culture of Kṛṣṇa consciousness untinged by philosophical speculation or fruitive activities. They are all understood to be pure devotees, and those among them who simply engage in conjugal love are called mādhurya-bhaktas, or internal devotees. The loving services in parental love, fraternity and servitude are included in conjugal love of God. In conclusion, therefore, every confidential devotee is a pure devotee of the Lord.
(Sri Caitanya Caritamrta------1:7:18-19-------purport).

The words viṣṇor ārādhanam refer to the worship of Lord Viṣṇu, or Kṛṣṇa. Thus the supreme form of worship is the satisfaction of the Supreme Personality of Godhead, Śrī Kṛṣṇa. It is further concluded that the worshiper of Lord Viṣṇu renders better service by worshiping the devotee of Lord Kṛṣṇa. There are different types of devotees—those in śānta-rasa, dāsya-rasa, sakhya-rasa, vātsalya-rasa and mādhurya-rasa. Although all the rasas are on the transcendental platform, mādhurya-rasa is the supreme transcendental mellow. Consequently it is concluded that the worship of devotees engaged in the Lord's service in mādhurya-rasa is the supreme spiritual activity. Śrī Caitanya Mahāprabhu and His followers mainly worship Lord Kṛṣṇa in mādhurya-rasa. Other Vaiṣṇava ācāryas recommended worship up to vātsalya-rasa. Therefore Śrīla Rūpa Gosvāmī in his Vidagdha-mādhava (1.2) describes Śrī Caitanya Mahāprabhu's cult as supreme:
anarpita-carīṁ cirāt karuṇayāvatīrṇaḥ kalau
samarpayitum unnatojjvala-rasāṁ sva-bhakti-śriyam
Śrī Caitanya Mahāprabhu appeared in this Age of Kali to exhibit the superexcellence of mādhurya-rasa, a gift never previously bestowed by any ācārya or incarnation. Consequently Śrī Caitanya Mahāprabhu is accepted as the most magnanimous incarnation. It is He only who distributed love of Kṛṣṇa while exhibiting the superexcellence of loving Kṛṣṇa in the conjugal rasa.
(Sri Caitanya Caritamrta------2:11:31-------purport).

Madhura-rati, or attachment in conjugal love, is described as follows:
mitho harer mṛgākṣyāś ca sambhogasyādi-kāraṇam
madhurāpara-paryāyā priyatākhyoditā ratiḥ
asyāṁ kaṭākṣa-bhrū-kṣepa-priya-vāṇī-smitādayaḥ
Madhura-rati, the conjugal relationship experienced between the Supreme Personality of Godhead and the young damsels of Vrajabhūmi, continuously exists in eight kinds of remembrances. This intimate relationship brought about by conjugal love produces movements of the eyebrows, glancing, sweet words and exchanges of joking words.
(Sri Caitanya Caritamrta------2:19:183-------purport).

"O Kṛṣṇa, O wonderful flute player, the beauty of Your boyhood activities is very wonderful in this world. You know the agitation of my mind, and I know what You are. No one knows how confidential our relationship is. Although my eyes are anxious to see You and Your face, I cannot see You. Please let me know what I shall do." A similar passage appears in Bhakti-rasāmṛta-sindhu (1.3.38) in which Rūpa Gosvāmī states:
rodana-bindu-maranda-syandi-
dṛgindīvarādya govinda
tava madhura-svara-kaṇṭhī
gāyati nāmāvalīṁ bālā
"O Govinda! This young girl with tears in her eyes is crying in a sweet voice, chanting Your glories." Such pure devotees are always anxious to describe the glories of Kṛṣṇa and to live in a place where He exhibited His pastimes. A similar verse appears again in kṛṣṇa-karṇāmṛta (92): "The body of Kṛṣṇa is so nice, and His face is so beautiful. Everything about Him is sweet and fragrant." And in Bhakti-rasāmṛta-sindhu (1.2.156): "O lotus-eyed one, when will I be able to always chant Your holy name, and being inspired by that chanting, when will I be able to dance on the banks of the Yamunā?"
(Teachings of Lord Caitanya).