Later in that chapter (adi-lila 1.94–101), the author elucidates that text in eight verses:
“All kinds of activities, both auspicious and inauspicious, that are detrimental to the discharge of transcendental loving service to Lord Sri Krishna are actions of the darkness of ignorance.” (1.94)
Srila Prabhupada’s Purport: “The poetical comparison of Lord Caitanya and Lord Nityananda to the sun and moon is very significant. The living entities are spiritual sparks, and their constitutional position is to render devotional service to the Supreme Lord in full Krishna consciousness. So-called pious activities and other ritualistic performances, pious or impious, as well as the desire to escape from material existence, are all considered to be coverings of these spiritual sparks. The living entities must get free from these superfluous coverings and fully engage in Krishna consciousness.
“The purpose of the appearance of Lord Caitanya and Lord Nityananda is to dispel the darkness of the soul. Before Their appearance, all these superfluous activities of the living entities were covering Krishna consciousness, but after the appearance of these two brothers, people’s hearts are becoming cleansed, and they are again becoming situated in the real position of Krishna consciousness.”
Krishnadasa Kaviraja Goswami continues:
“By the grace of Lord Caitanya and Lord Nityananda, this darkness of ignorance is removed and the truth is brought to light.” (1.95)
“The Absolute Truth is Sri Krishna, and loving devotion to Sri Krishna exhibited in pure love is achieved through congregational chanting of the holy name, which is the essence of all bliss.” (1.96)
“The sun and moon dissipate the darkness of the external world and thus reveal external material objects like pots and plates.” (1.97)
“But these two brothers [Lord Caitanya and Lord Nityananda] dissipate the darkness of the inner core of the heart, and thus They help one meet the two kinds of bhagavatas [persons or things in relationship with the Personality of Godhead].” (1.98)
“One of the bhagavatas is the great scripture Srimad-Bhagavatam, and the other is the pure devotee absorbed in the mellows of loving devotion.” (1.99)
“Through the actions of these two bhagavatas the Lord instills the mellows of transcendental loving service into the heart of a living being, and thus the Lord, in the heart of His devotee, comes under the control of the devotee’s love.” (1.100)
“The first wonder is that both brothers appear simultaneously, and the other is that They illuminate the innermost depths of the heart.” (1.101)