The young people in the Hare Kṛṣṇa movement chant the Hare Kṛṣṇa mantra all the time. If this mantra were material, how long would they chant it? It is not possible to chant a material name for very long because the chanting would become hackneyed and very tiresome. No one could be satisfied simply by chanting Hare Kṛṣṇa unless Hare Kṛṣṇa itself were spiritual. We may chant, “Mr. John, Mr. John, Mr. John,” but after an hour we will be fed up. However, the more we become spiritually advanced, the more bliss we will derive from chanting Hare Kṛṣṇa." Śrīla Prabhupāda in Teachings of Lord Kapila, Chapter 13, purport to Text 29

“Consumption of food, sleeping, fear and sexual enjoyment are the common attributes of both humans and animals. But the special attribute of humans is the ability to acknowledge the principles of Dharma. Bereft of Dharma, a person is no better than the animals.” (Hitopadesha, 25)

"I always bow to the Guru, who exudes bliss, who is pure and bright, whose nature is knowledge, and who is awake to the true self. Lord of Yogis, adorable and worthy of worship, the Guru is the physician who cures the disease of the countless cycles of birth, death, and rebirth." (Guru Gita, 93)

There is no harm. Simply give Me the results.” As stated in Bhagavad-gītā (9.27):
yat karoṣi yad aśnāsi
yaj juhoṣi dadāsi yat
yat tapasyasi kaunteya
tat kuruṣva mad-arpaṇam
“O son of Kuntī, all that you do, all that you eat, all that you offer and give away, as well as all austerities that you may perform, should be done as an offering unto Me.”"
Śrīla Prabhupāda in Teachings of Lord Kapila, Chapter 21, purport to Text 24

"The greatest wealth is the wealth of wisdom, and the greatest poverty is the poverty of ignorance" (Mahabharata, Shanti Parva, 148.14)

"One-pointedness is steadfastness of the mind. Unbroken continuation of that mental ability is meditation. That same meditation when there is only consciousness of the object of meditation and not of the mind is realization. The three appearing together are self-control." (Yoga Sutras, 3.1-4)

"Spirituality must always be coupled with discernment (viveka), the ability to use our keen intellects and philosophical sense to separate truth from falsehood, the real from the apparent, light from dark, good from evil. The heart and intellect must operate together. Philosophy is not sufficient for knowing Truth, but it is necessary. Only with such a healthy balance can we approach the Truth." - Sri Dharma Pravartaka Acharya

“Meditation with love is what is understood to be bhakti. Worship offered without loving devotion is as good as not having offered at all. Loving devotion is regarded as consisting of eight integral parts. This is especially true regarding devotion to Lord Vishnu, by attaining to which (Vishnubhakti), one gains the supreme siddhi (perfection) quickly. The eight integral parts of devotion are: (1) The daily worship of God. (2) The preservation of the rules of the sangha (community). (3) Love toward the devotees of Lord Vishnu (4) Great enthusiasm for the worship of Lord Vishnu. (5) Determination in the performance of worship. (6) Eagerness to hear divine stories relating to Lord Vishnu. (7) Absence of the desire to harm others. Finally, (8) not making a materialistic business out of the worship of Lord Vishnu. These make up the eight features of bhakti as seen in man.” (Parama-Samhita Pancharatra, 4.71B-75)

“The syllable 'Aum' is the door of heaven. Therefore he who is about to study the Veda, shall begin (his lesson) by (pronouncing) it.” (Apastamba Sutra, Prashna One, 4.13.6)

Human life is meant to get rid of anarthas, unwanted things, but where is the university or college where this science of purification is taught? The only institution is this Kṛṣṇa consciousness society. Kṛṣṇa is within the heart, and the contaminations are also there, but Kṛṣṇa will help us cleanse them. Naṣṭa-prāyeṣv abhadreṣu nityaṁ bhāgavata-sevayā (Bhāg. 1.2.18). We must regularly hear Śrīmad-Bhāgavatam and chant Hare Kṛṣṇa; these are the two processes recommended by Caitanya Mahāprabhu. Haridāsa Ṭhākura was chanting three hundred thousand holy names a day, but we have fixed the number at sixteen rounds. Nonetheless, we are so unfortunate and fallen that we cannot even perform them. We should not waste our time reading and talking nonsense, but should engage in the study of Śrīmad-Bhāgavatam. Our time is very valuable, and we should not waste it."
Śrīla Prabhupāda in Teachings of Lord Kapila, Chapter 9, purport to Text 15