The two words are there in the Vedic literature: one is brāhmin and one is kṛpaṇa. Kṛpaṇa means miser, and brāhmin means liberal, broad-minded. Brahma jānāti iti brāhmaṇaḥ, or one who knows the Supreme, the Absolute Truth, he's brāhmin. And one who does not know, that is animal. This is the difference between animal and man.
Man should be educated to understand the Absolute Truth. Therefore in the human society there is school, colleges, universities, philosophers, scientists, mathematician. Because human life is meant for knowledge. The animal life, they're not required to take education. They are simply busy with how . . . with the business how to eat, how sleep, how to mate and how to defend. That's all.
So the tapasya life begins from celibacy, brahmacaryeṇa. Śukadeva Gosvāmī recommends. Brahmacarya is described in the śāstras that smaraṇaṁ kīrtanaṁ keliḥ prekṣaṇaṁ guhyam āsanam. Sex life, smaraṇam, thinking of sex life, that is against brahmacarya. Complete celibacy means one should not think of even sex life. Smaraṇam. Or talk of sex life.
Our modern literature, newspaper and everything, simply full with talks of sex life, this is against brahmacarya life. Smaraṇaṁ kīrtanaṁ keli. And actually indulging in sex life. Prekṣaṇam: looking, overlooking a nice boy or nice girl, that is also against brahmacarya. Guhyam āsanam: whispering between girls and boys, that is also against brahmacārī. Guhyam āsanaṁ saṅkalpam. Then determination of sex life. Vyavasāya: endeavoring how to effect sex life. So when we can stop all these activities, that is real brahmacarya.
It is very difficult at the present age. Etad maithunyam aṣṭāṅgaṁ pravadanti manīṣinaḥ vikārita brahmacaryam eda astanam lakṣaṇam iti. So brahmacarya means that you cannot think of sex life, you cannot talk of sex life, you cannot whisper about sex life or you cannot endeavor for sex life. These eight types of activities in sex indulgence are against brahmacārī life. But here it is prescribed that if you want to make solution of the problems of life, then you adopt . . . you have to adopt a life of tapasya, austerity, which begins from brahmacārī.
To summarize this brahmacarya life in this age, we have given a simple formula, that "No illicit sex." Sex is there. Sex is not bad. In the Bhagavad-gītā it is said, dharmāviruddhaḥ kāmo 'smi (BG 7.11): "Sex life which is not against the religious principles of life, that is I am." Kṛṣṇa says.
So dharmāviruddha, according to Vedic civilization, one should have sex indulgence only once in a month. That is the prescription. And when the wife is pregnant there is no sex life. That is dharmāviruddha. That is not against the religious principles. Even in your life, married life, if you indulge sex life more than once in a month, or in pregnancy, that is against religious principle.