(1) Five nights and five days. Vatsar (a year) is 12 x 30 = 360 days and a civil year is with 5 or 6 extra days at the end. These 5-6 days and nights are called Pancha-raatra or Shadaha.

(2) A Hindu sect, perhaps as ancient as 100AD, which believed in one God and emphasized the path of devotion. Their deity was Vishnu who was also called as Naaraayan, Hari, Vaasudev, and Krishn. This sect did not believe in sacrifice and torture of the body to please God. In all these things it represented the best of Hinduism as it evolved after the age of Upanishad. Later it got corrupted by Taantrik doctrines and lost its flavor.
[Aangiras, p 209]

(3) Panch-Raatra states that the personality of Jeev called Sankarshan has emerged from Vaasudev, the supreme cause of all causes; Pradyumn, the mind, has come from Sankarshan, and that Aniruddh, the ego, has come from Pradyumn. But one cannot say that the living entity (Jeev) takes birth or is created, for such a statement is against the injunction of the Ved. As stated in the Kath Upanishad (2.18), living entities, as individual spiritual souls, can have neither birth nor death. All Vaidik literature declares that the living entities are eternal. Therefore when it is said that Sankarshan is Jeev, this indicates that He is the predominating Deity of the living entities. Similarly, Pradyumn is the predominating Deity of the mind, and Aniruddh is the predominating Deity of the ego.

"It has been said that Pradyumn, the mind, was produced from Sankarshan. But if Sankarshan were a living entity, this could not be accepted, because a living entity cannot be the cause of the mind. The Vaidik injunctions state that everything, including life, mind and the senses comes from the Supreme Personality of Godhead. It is impossible for the mind to be produced by a living entity, for the Ved state that everything comes from the Absolute Truth, the Supreme Lord.

"Sankarshan, Pradyumn and Aniruddh have all the potent features of the absolute Personality of Godhead, according to the revealed scriptures, which contain undeniable facts that no one can refute. Therefore these members of the quadruple manifestation are never to be considered ordinary living beings. Each of Them is a plenary expansion of the Absolute Godhead, and thus each is identical with the Supreme Lord in knowledge, opulence, energy, influence, prowess and potencies.

“The evidence of the Panch Raatra (there are many) cannot be neglected. Only untrained persons who have not genuinely studied the Panch Raatra think that the Panch Raatra contradict the Shruti regarding the birth or beginning of the living entity. In this connection, we must accept the verdict of Shree-mad Bhaagavat, which says, "The absolute Personality of Godhead, who is known as Vaasudev and who is very affectionate toward His surrendered devotees, expands Himself in quadruple forms who are subordinate to Him and at the same time identical with Him in all respects." The Paushkar Sanhitaa states, "The scriptures that recommend that Braahman worship the quadruple forms of the Supreme Personality of Godhead are called Agam."

In all Vaishnav literature it is said that worshiping these quadruple forms is as good as worshiping the Supreme Personality of Godhead Vaasudev who in His different expansions, complete in six opulence, can accept offerings from His devotees of the results of their prescribed duties.

“Worshiping the expansions for pastimes, such as Nrasinh, Raam, Shesh and Koorm, promotes one to the worship of the Sankarshan quadruple. From that position one is raised to the platform of worshiping Vaasudev, the Supreme Brahm. In the Paushkar Sanhitaa it is said, "If one fully worships according to the regulative principles, one can attain the Supreme Personality of Godhead, Vaasudev." It is to be accepted that Sankarshan, Pradyumn and Aniruddh are as good as Lord Vaasudev, for they all have inconceivable power and can accept transcendental forms like Vaasudev. Sankarshan, Pradyumn and Aniruddh are never born, but they can manifest themselves in various incarnations before the eyes of pure devotees. This is the conclusion of all Vaidik literature.

“That the Lord can manifest Himself before His devotees by His inconceivable power is not against the teaching of the Panch Raatra. Since Sankarshan, Pradyumn and Aniruddh are, respectively, the predominating Deities of all living entities, the total mind and the total ego, the designation of Sankarshan, Pradyumn and Aniruddh as "Jeev", "mind" and "ego" are never contradictory to the statements of the scriptures. These terms identify these Deities, just as the terms "sky" and "light" sometimes identify the Absolute Brahm.

The scriptures completely deny the birth or production of the living entity. In the Param Sanhitaa it is described that material nature, which is used for others' purposes, is factually inert and always subject to transformation. The field of material nature is the arena of the activities of fruitive actors, and since the material field is externally related with the Supreme Personality of Godhead, it is also eternal. In every Sanhitaa, the Jeev (living entity) has been accepted as eternal, and in the Panch Raatra the birth of the Jeev is completely denied. Anything that is produced must also be annihilated. Therefore if we accept the birth of the living entity, we also have to accept his annihilation. But since the Vaidik literatures say that the living entity is eternal, one should not think the living being to be produced at a certain time. In the beginning of the Param Sanhitaa it is definitely stated that the face of material nature is constantly changeable. Therefore "beginning," "annihilation" and all such terms are applicable only in the material nature.

In this connection the commentary of Sridhar Svami on Shree-mad Bhaagavat (3.1.34) is very helpful. For a detailed refutation of Shankarachaarya's arguments attempting to prove Sankarshan an ordinary living being, one may refer to Srimat Sudarshanaachaarya's commentary on the "Shree Bhaashya", which is known as the Shrut Prakaashikaa.
(Shree Chaitanya-Charitaamrit Aadi-leelaa, 5.41 purport by Srila Prabhupaad Bhaktivedaant Swaamee Mahaaraaj)