Lord Rishabh Dev, the incarnation of the Lord as a great King, in His teachings to His one hundred sons gave this valuable instruction,
nāyaṁ deho deha-bhājāṁ nṛloke
kaṣṭān kāmān arhate viḍ-bhujāṁ ye
tapo divyaṁ putrakā yena sattvaṁ
śuddhyed yasmād brahma-saukhyaṁ tv anantam
“Lord Ṛṣabhadeva told His sons: My dear boys, of all the living entities who have accepted material bodies in this world, one who has been awarded this human form should not work hard day and night simply for sense gratification, which is available even for dogs and hogs that eat stool. One should engage in penance and austerity to attain the divine position of devotional service. By such activity, one’s heart is purified, and when one attains this position, he attains eternal, blissful life, which is transcendental to material happiness and which continues forever.” Srimad Bhagavatam 5.5.1
Everyone wants happiness. That is the natural position of the soul. However, in the material condition, the soul is enclosed in gross and subtle material coverings. The basic nature of the material energy is pain & ephemerality (duḥkhālayam aśāśvatam – BG 8.15). Hence these two qualities afflict the material coverings of the soul as well. Yet, the world is so influenced by the Lord’s illusory energy (maya) that all living beings are busy trying to screw out happiness from an existence that is fundamentally painful, Needless to say their every effort of mundane happiensss is doomed to failure from the very inception. Of course, the living entity chooses to come under the influence of the material energy by his desire to lord over. It is important for the soul to change his choices. Such a change of choice is possible in the human form.
Hence, Lord Rishabh Dev instructs human society (nṛloke) not to indulge the material senses. Such gratifications he says are fit only for the stool eating hogs and dogs. He teaches that the only purpose of the human body is to engage in transcendental austerity (tapo divyaṁ), which involves sense restraint, spiritual practice and knowledge cultuvation by which the human being may attain the position of eternal spiritual happiness (brahma-saukhyaṁ anantam).
Vaishnavas are persons trying to cultivate pure devotional service of the Supreme Personality of Godhead, Krishna. Tapasya is an important aspect of the lives of Vaishnavas. One of the austerities that Vaishnava devotees observe is fasting on the eleventh day of the waxing and waning moons. Srila Prabhupada speaking in a lecture on the Bhagavad-Gita 7.9 said, “tapasya means to undergo voluntarily some inconveniences of this body. Because we are accustomed to enjoy bodily senses, and tapasya means voluntarily to give up the idea of sense gratification. That is tapasya. tapasya. Just like Ekadasi. Ekadasi, one day fasting, fortnight. That is also tapasya. Or fasting in some other auspicious day. That tapasya is good, even for health, and what to speak of advancing in Krishna consciousness. So we should accept this tapasya. . .There are many prescribed days for fasting. We should observe.”
Similarly Chaturmasya is a four-month period of transcendental austeritiies for the Vaishnava devotee followers of Lord Chaitanya Mahaprabhu. Srila Prabhupada teaches about the austeries of Chaturmasya as follows,
“The Caturmasya period begins in the month of Ashadha (June-July) from the day of Ekadasi called Sayana-ekadasi, in the fortnight of the waxing moon. The period ends in the month of Kartika (October-November) on the Ekadasi day known as Utthana-ekadasi, in the fortnight of the waxing moon. This four-month period is known as Caturmasya. Some Vaishnavas also observe it from the full-moon day of Ashadha until the full-moon day of Kartika. That is also a period of four months. This period, calculated by the lunar months, is called Caturmasya, but others also observe Caturmasya according to the solar month from Sravana to Kartika. The whole period, either lunar or solar, takes place during the rainy season. Caturmasya should be observed by all sections of the population. It does not matter whether one is a grihastha or a sannyasi. The observance is obligatory for all asramas. The real purpose behind the vow taken during these four months is to minimize the quantity of sense gratification. This is not very difficult. In the month of Sravana one should not eat spinach, in the month of Bhadra one should not eat yogurt, and in the month of Asvina one should not drink milk. One should not eat fish or other nonvegetarian food during the month of Kartika. A nonvegetarian diet means fish and meat. Similarly, masura dal and urad dal are also considered nonvegetarian. These two dals contain a great amount of protein, and food rich in protein is considered nonvegetarian. On the whole, during the four-month period of Caturmasya one should practice giving up all food intended for sense enjoyment.
If we can restrain our senses from sinful activities like meat-eating, intoxication, illicit sex and gambling and then observe the austerities of Ekadasi and Chaturmasya, while performing devotional service to Krishna, especially by regularly chanting Hare Krishna Maha Mantra a fixed number of times daily, then even in the spiritually decrepit circumstances of Kali Yuga, we can advance towards the eternal destination, the point of pure devotional service to the Supreme Lord, Sri Krishna.