Srimad Bhagavatam Canto 07, Chapter 05, Text 30

SB 7.5.30

sri-prahrada uvaca
matir na krsne paratah svato va
 mitho ’bhipadyeta grha-vratanam
adanta-gobhir visatam tamisram
 punah punas carvita-carvananam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Prahlada Maharaja replied: Because of their uncontrolled senses, persons too addicted to materialistic life make progress toward hellish conditions and repeatedly chew that which has already been chewed. Their inclinations toward Krsna are never aroused, either by the instructions of others, by their own efforts, or by a combination of both.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
In this verse the words matir na krsne refer to devotional service rendered to Krsna. So-called politicians, erudite scholars and philosophers who read Bhagavad-gita try to twist some meaning from it to suit their material purposes, but their misunderstandings of Krsna will not yield them any profit. Because such politicians, philosophers and scholars are interested in using Bhagavad-gita as a vehicle for adjusting things materially, for them constant thought of Krsna, or Krsna consciousness, is impossible (matir na krsne). As stated in Bhagavad-gita (18.55), bhaktya mam abhijanati: only through devotional service can one understand Krsna as He is. The so-called politicians and scholars think of Krsna as fictitious. The politician says that his Krsna is different from the Krsna depicted in Bhagavad-gita. Even though he accepts Krsna and Rama as the Supreme he thinks of Rama and Krsna as impersonal because he has no idea of service to Krsna. Thus his only business is punah punas carvita-carvananam — chewing the chewed again and again. The aim of such politicians and academic scholars is to enjoy this material world with their bodily senses. Therefore it is clearly stated here that those who are grha-vrata, whose only aim is to live comfortably with the body in the material world, cannot understand Krsna. The two expressions grha-vrata and carvita-carvananam indicate that a materialistic person tries to enjoy sense gratification in different bodily forms, life after life, but is still unsatisfied. In the name of personalism, this ism or that ism, such persons always remain attached to the materialistic way of life. As stated in Bhagavad-gita (2.44):
vyavasayatmika buddhih
 samadhau na vidhiyate
“In the minds of those who are too attached to sense enjoyment and material opulence, and who are bewildered by such things, the resolute determination for devotional service to the Supreme Lord does not take place.” Those who are attached to material enjoyment cannot be fixed in devotional service to the Lord. They cannot understand Bhagavan, Krsna, or His instruction, Bhagavad-gita. Adanta-gobhir visatam tamisram: their path actually leads toward hellish life.
As confirmed by Rsabhadeva, mahat-sevam dvaram ahur vimukteh: one must try to understand Krsna by serving a devotee. The word mahat refers to a devotee.
mahatmanas tu mam partha
 daivim prakrtim asritah
bhajanty ananya-manaso
 jñatva bhutadim avyayam
“O son of Prtha, those who are not deluded, the great souls, are under the protection of the divine nature. They are fully engaged in devotional service because they know Me as the Supreme Personality of Godhead, original and inexhaustible.” (Bg. 9.13) A mahatma is one who is constantly engaged in devotional service, twenty-four hours a day. As explained in the following verses, unless one adheres to such a great personality, one cannot understand Krsna. Hiranyakasipu wanted to know where Prahlada had gotten this Krsna consciousness. Who had taught him? Prahlada sarcastically replied, “My dear father, persons like you never understand Krsna. One can understand Krsna only by serving a mahat, a great soul. Those who try to adjust material conditions are said to be chewing the chewed. No one has been able to adjust material conditions, but life after life, generation after generation, people try and repeatedly fail. Unless one is properly trained by a mahat — a mahatma, or unalloyed devotee of the Lord — there is no possibility of one’s understanding Krsna and His devotional service.”
Srimad Bhagavatam Canto 07, Chapter 05, Text 29
Srimad Bhagavatam Canto 07, Chapter 05, Text 31