SB 11.21.7

deśa-kālādi-bhāvānāṁ
 vastūnāṁ mama sattama
guṇa-doṣau vidhīyete
 niyamārthaṁ hi karmaṇām
Word for word: 
deśa — of space; kāla — time; ādi — and so on; bhāvānām — of such states of existence; vastūnām — of things; mama — by Me; sat-tama — O most saintly Uddhava; guṇa-doṣau — piety and sin; vidhīyete — are established; niyama-artham — for the restriction; hi — certainly; karmaṇām — of fruitive activities.
Translation: 
O saintly Uddhava, in order to restrict materialistic activities, I have established that which is proper and improper among all material things, including time, space and all physical objects.
Purport: 

The word niyamārtham (“in order to restrict”) is significant in this verse. A conditioned soul falsely identifies with his material senses and thus considers anything giving immediate satisfaction to the body to be good and anything inconvenient or disturbing to be bad. By higher intelligence, however, one recognizes long-term self-interest and danger. For example, medicine may be immediately bitter, but by calculating one’s long-term interest one accepts the bitter medicine to cure a disease that is not immediately troublesome but ultimately fatal. Similarly, Vedic literature restricts the sinful propensities of human beings by establishing what is proper and what is improper among all the objects and activities of the material world. Because everyone must eat, the Vedas prescribe foods in the mode of goodness and not those which are sinful, such as meat, fish and eggs. Similarly, one is advised to live in a peaceful and pious community and not in association with sinful persons, nor in an unclean or turbulent environment. By designating and restricting the exploitation of the material world, Vedic knowledge gradually brings a conditioned soul to the platform of material goodness. At that stage one becomes eligible to serve the Supreme Personality of Godhead and enter the transcendental stage of life. It should be remembered that such mere eligibility does not constitute actual qualification; without Kṛṣṇa consciousness mere mundane piety can never qualify a conditioned soul to go back home, back to Godhead. Within this world we are all infected by false pride, which must be diminished through submission to the Vedic injunctions. One who is completely engaged in the loving service of the Lord need not adopt these preliminary methods, for he directly contacts the Personality of Godhead through the spontaneous process of surrender. In the previous verse the Lord explained why Vedic literatures assign different values to the bodies of different living entities, and here the Lord explains the Vedic value system in regard to the material objects that interact with these bodies.