You can keep one dog in a royal position, but as soon as it will see one shoe there, immediately bite—because he's a dog. The doggish quality's there. You may put him on the throne; that's doesn't matter. But the doggish quality you cannot change.
Similarly this svabhāva. Svabhāva means the material nature. Material nature. We have acquired so many material nature by association of the three modes of material nature: sattva-guṇa, rajo-guṇa, tamo-guṇa. So our habits are formed on account of our association with the three different qualities of material nature. But if we can disassociate ourself from the three modes of material nature, then our real nature, means spiritual nature, becomes invoked.
That is the process of Kṛṣṇa consciousness. If you remain Kṛṣṇa conscious, then there is no chance of your associating with the three material modes of nature. That is the secret. Therefore you'll find our students, those who are habituated to so many bad things previously, they are able to stay in a platform where there is no such contamination.