The material world is full of contaminations (Chapter 3 Text 13)
- Hare Krishna Friends,Chapter 3: Karma-yoga
annad bhavanti bhutani
yajnad bhavati parjanyo
annat--from grains; bhavanti--grow; bhutani--the material bodies; parjanyat--from rains; anna--of food grains; sambhavah--are made possible; yajnat--from the performance of sacrifice; bhavati--becomes possible; parjanyah--rains; yajnah--performance of yajna; karma--prescribed duties; samudbhavah--born of.
All living bodies subsist on food grains, which are produced from rains. Rains are produced by performance of yajna [sacrifice], and yajna is born of prescribed duties.
Srila Baladeva Vidyabhusana, a great commentator on the Bhagavad-gita, writes as follows: ye indrady-angatayavasthitam yajnam sarvesvaram visnum abhyarcya tac-chesam asnanti tena tad deha-yatram sampadayanti, te santah sarvesvarasya yajna-purusasya bhaktah sarva-kilbisair anadikala-vivrddhair atmanubhava-prati bandhakair nikhilaih papair vimucyante.
The Supreme Lord, who is known as the yajna-purusa, or the personal beneficiary of all sacrifices, is the master of all demigods, who serve Him as the different limbs of the body serve the whole. Demigods like Indra, Candra, Varuna, etc., are appointed officers who manage material affairs, and the Vedas direct sacrifices to satisfy these demigods so that they may be pleased to supply air, light and water sufficiently to produce food grains. When Lord Krsna is worshiped, the demigods, who are different limbs of the Lord, are also automatically worshiped; therefore there is no separate need to worship the demigods. For this reason, the devotees of the Lord, who are in Krsna consciousness, offer food to Krsna and then eat--a process which nourishes the body spiritually. By such action not only are past sinful reactions in the body vanquished, but the body becomes immunized to all contamination of material nature. When there is an epidemic disease, an antiseptic vaccine protects a person from the attack of such an epidemic. Similarly, food offered to Lord Visnu and then taken by us makes us sufficiently resistant to material affection, and one who is accustomed to this practice is called a devotee of the Lord.
Therefore, a person in Krsna consciousness, who eats only food offered to Krsna, can counteract all reactions of past material infections, which are
impediments to the progress of self-realization. On the other hand, one who does not do so continues to increase the volume of sinful action, and this prepares the next body to resemble hogs and dogs, to suffer the resultant reactions of all sins. The material world is full of contaminations, and one who is immunized by accepting prasadam of the Lord (food offered to Visnu) is saved from the attack, whereas one who does not do so becomes subjected to contamination. Food grains or vegetables are factually eatables. The human being eats different kinds of food grains, vegetables, fruits, etc., and the
animals eat the refuse of the food grains and vegetables, grass, plants, etc. Human beings who are accustomed to eating meat and flesh must also depend on the production of vegetation in order to eat the animals.
Therefore, ultimately, we have to depend on the production of the field and not on the production of big factories. The field production is due to sufficient rain from the sky, and such rains are controlled by demigods like Indra, sun, moon, etc., and they are all servants of the Lord. The Lord can be satisfied by sacrifices; therefore, one who cannot perform them will find himself in scarcity--that is the law of nature. Yajna, specifically the sankirtana-yajna
prescribed for this age, must therefore be performed to save us at least from scarcity of food supply.
Source As It Is by HDG. A.C. BhaktiVedanta Swami Srila Prabhupada