Modern men want to see everything with their eyes, although they are not sufficiently qualified. Consequently, they disbelieve in the existence of the demigods or of the Supreme God. They should see through the pages of authentic scriptures and should not simply believe their unqualified eyes. Even in these days, God can also be seen by qualified eyes tinged with the ointment of love of God.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Srimad-Bhagavatam 2.6.29, Purport

Actions performed only out of a sense of duty have their effect only on the mind, intelligence, and false ego, whereas actions done in love and devotion, with attachment to the Supreme, have their effect on the soul. Pure attachment, devotional service, emanates from the soul.
Srila Bhaktisiddhanta Sarasvati Thakura
Uncommon Conversations, Conversation 7

O learned Uddhava, those who fix their consciousness on Me, giving up all material desires, share with Me a happiness that cannot possibly be experienced by those engaged in sense gratification.
Lord Sri Krishna
Srimad-Bhagavatam 11.14.12

Association with a devotee, the mercy of Krishna, and the nature of devotional service help one to give up all undesirable association and gradually attain elevation to the platform of love of Godhead.
Sri Chaitanya Mahaprabhu
Sri Chaitanya-charitamrita, Madhya-lila 24.104

In an assembly of pure devotees, there is no question of discussing material subjects like politics and sociology. In an assembly of pure devotees, there is discussion only of the qualities, forms, and pastimes of the Supreme Personality of Godhead. He is praised and worshiped with full attention. In the association of pure devotees, by constantly hearing such topics respectfully, even a person who wants to merge into the existence of the Absolute Truth abandons this idea and gradually becomes attached to the service of Vasudeva.
Jada Bharata
Srimad-Bhagavatam 5.12.13

Let the poets continue to rave about poetry, and let the Vedic scholars incessantly praise the nectar derived from Brahman realization. I myself will take shelter of a beautiful youth who is decorated with a garland made of wildflowers, holding a flute to His blossoming lips.
Srila Ishvara Puri
Srila Rupa Goswami’s Padyavali

He is neither large nor infinitesimal; yet He is larger and smaller than everything else. He is said to be devoid of color; yet He is dark blue, and the corners of His eyes are reddish. By the play of His personal powers, the Supreme Lord is known by contradictory designations. Yet He is the Supreme, and faults should never be ascribed to Him. In Him all contrary qualities combine.
Kurma Purana
Brihad-Bhagavatamrita 2.2.179, Commentary