If we try to hear glories of the Lord with the ear, then my ear may not be engaged in other songs. Paraṁ dṛṣṭvā nivartate (BG 2.59). Similarly, my tongue. If I determine that "I shall eat only foodstuff which is offered to Kṛṣṇa," then naturally my eating problem becomes restricted, and as I go on eating the foodstuff which is offered first to Kṛṣṇa and then I take, then, now, the natural effect will be that my tongue will be controlled.
And if I want to control my other senses, then the tongue control is the first business, because if we cannot control the tongue, then other senses is impossible to be controlled. Therefore we, when we take our foodstuff, we sing this nice song, śarīra abidyā-jāl, joḍendriya tāhe kāl—"This body is a network of nescience." Śarīra abidyā-jāl, joḍendriya tāhe kāl: "And the material senses, they are just like kāla." Kāla means venomous serpents.
So śarīra abidyā-jāl, joḍendriya tāhe kāl, tā'ra madhye jihwā ati, lobhamoy sudurmati; "Amongst all the senses, the tongue is very avaricious." You see? It is . . . it is . . . it wants so many palatable dishes now and then. Tā'ra madhye jihwā ati, lobhamoy sudurmati: "And it is very difficult to control." Now, kṛṣṇa baḍo doyāmoy: "So Kṛṣṇa, Lord Kṛṣṇa, is so kind that in order to control my senses, tongue, first, He has given me so many nice foodstuff so that if I eat them, then my tongue will be controlled."
So the whole thing is tāni sarvāṇi saṁyamya yukta āsīta mat-paraḥ. We should always remember that . . . that to attain to the spiritual life, it is a great penance. It is a great penance. But although it is very difficult, although it is very difficult . . . Perhaps you know that in, in the Purāṇas, in the Vedic literature, we have got information that there are sages who underwent penance for so many, many years.
Why in the history or the Purāṇas? You can see from the examples of Lord Buddha, Lord Jesus Christ, Lord Caitanya, Śaṅkarācārya, who were recently within the limit of our historical knowledge. They attained spiritual perfection after undergoing penances for many, many years.