(Srila Prabhupada applying tilaka—click to enlarge)
Guest: What is the proper spiritual attitude toward rodents, reptiles and disease-bearing insects? What should be the proper spiritual attitude toward those?
Devotee (2): "What is the spiritual attitude towards reptiles, rodents..."
Devotee (3): (explaining) Disease-bearing in animals, something that is diseased and can give you a disease, what is your..., what is the Vedic attitude towards protection from these animals?
Prabhupāda: Protection? Cleanliness. Just like if you keep your apartment very cleansed, if you keep your clothes and body very cleansed, you won't find this insect disturbing you. Just like the flies, they go in a nasty place. So you should be cleansed. You should take protection in that way. You cannot kill them. The cockroaches, the modern method of bathroom attached in 600th floor... So (laughs) this is unclean. Therefore the cockroaches are born there. You see?
So if you keep yourself clean, there will be no more disturbances. The incense will keep off all insects. You make fresh food, there will be no germs. You take warm, immediately prepared, that is germicide foodstuff. But if you keep for months together in the refrigerator, that will contaminate with germ, disease.
Therefore the brahminical culture means cleanliness is next to godliness. You have to keep your body clean, you have to keep your apartment clean, everything clean, and there will be no more disturbance. Bahyābhyantaraḥ śuciḥ. The Vedic literature says that you should keep yourself externally and internally cleansed. Externally, you can keep yourself clean by soap, water and change of dress, washed dress, externally. And internally, by thinking of Kṛṣṇa. Then there will be no more disturbance.
apavitraḥ pavitro vāsarvāvasthāṁ gato 'pi vāyaḥ smaret
puṇḍarīkākṣaṁsa bahyābhyantaraḥ śuciḥ
Śuciḥ means cleansed. Therefore we prescribe so many things just to keep you cleansed—cleansed within, cleansed outside. Then there is no affection (infection) of māyā. Otherwise, you will be harassed by three kinds of miserable condition: adhyātmika, adhibhautika... I have seen many persons in India, within two or three days, by perspiration within their coat, they germinate so many germs. Do not take bath, unclean. You see? So cleanliness is the protection from infection. And water is very disinfectant, natural disinfectant. This is the medical opinion: water. Therefore God has supplied unlimited quantity of water. You can spend it as much as you like.
Guest: Aren't they allowed to boil water in India?
Prabhupāda: Yes, why not?
Guest: In boiling the water, do you kill any little insects that are in the water?
Prabhupāda: Yes. But that I have already explained, that we are killing every moment. Therefore we have to keep from the reaction by Kṛṣṇa consciousness. You cannot avoid killing. Whenever we are cooking, we are killing so many germs, the water. While we are burning fire, then so many germs are being killed. So the killing process cannot be stopped, but you should not do it willingly, and you should keep yourself God conscious. Then you are freed from the reaction.
(Srila Prabhupada Lecture, Los Angeles, December 4, 1968)