1180
Śrīmad-Bhāgavatam
[Canto 4, Ch. 25]
Such foolish persons are like animals because they do not know the process of sense enjoyment in this life and after death.
PURPORT
Since there are 8,400,000 species of life, there are also many different living conditions. In the lower grades of life (in plant and tree life) there is no system for sexual intercourse. In the upper grades (in the life of birds and bees) there is sex, but the insects and animals do not know how to actually enjoy sex life. In the human form of life, however, there is full knowledge of how to enjoy sex. Indeed, there are many so-called philosophers who give directions on how to enjoy sex life. There is even a science called  kāma-śāstra , which is the science of sex. In human life there are also such divisions as  brahmacarya ,  grhastha ,  vānaprastha , and  sannyāsa . There is no sex life except in the  grhastha  or householder  āśrama . The  brahmacārī  is not allowed any sex, a  vānaprastha  voluntarily refrains from sex, and the  sannyāsī  is completely renounced. The  karmīs  do not practice  brahmacarya ,  vānaprastha  or  sannyāsa  life, for they are very much interested in  grhastha  life. In other words, a human being is very much materially inclined. Indeed, all living entities are materially inclined. They prefer  grhastha  life because there is concession for sex. The  karmīs  think the other statuses of life are worse than animal life, for animals also have sex, whereas the  brahmacārī ,  vānaprastha  and  sannyāsī  completely give up sex. The  karmīs , therefore, abhor these orders of spiritual life.
TEXT 39
धर्मो ह्यत्रार्थकामौ च प्रजानन्दोऽमृतं यशः । लोका विशोका विरजा यान् न केवलिनो विदुः॥ ३९ ॥
dharmo hy atrārtha-kāmau ca prajānando 'mṛtam yaśaḥ lokā viśokā virajā yān na kevalino viduḥ
dharmaḥ—religious ritual; hi—certainly; atra—here in this  grhastha-āśrama , or householder life; artha—economic development; kāmau—sense gratification; ca—and; prajā-ānandaḥ—the pleasure of generations; amṛtam—the results of sacrifice; yaśaḥ—reputation; lokāḥ—planetary systems; viśokāḥ—without lamentation; virajāḥ—without disease; yān—which; na—never; kevalinaḥ—the transcendentalists; viduḥ—know.