By His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Ishopanishad teaches us that we should be very careful. We don't say that you shouldn't advance in material education. You can advance, but at the same time, become Krishna conscious. That is our propaganda. We don't say that you shouldn't manufacture cars or machines. But we say, "All right, you have manufactured this machine. Employ it in Krishna's service." That is our proposal. We don't say to stop it. We don't say that you cannot have any sex life. But we say, "Yes, have sex—for Krishna. You can have sex a hundred times to produce Krishna conscious children. But don't create cats and dogs." That is our proposal.