Sex is a basic human drive. Propagation is creation, an activity linked with the gods. But because it can so easily get out of control, most religions have a difficult time deciding how to deal with it. Some, such as traditional monotheistic religions, generally look upon sex as a necessary evil and tightly fence it in with rules and regulations.
Other religions, such as Hinduism, have tended to celebrate it, recognizing powerful divine forces at work. Shiva (see Hinduism) is the Hindu god most often pictured with the phallic symbols of lingam and yoni, stylizations of male and female sexual organs. The lingam is often pictured as the shaft upon which the wheel of samsara, the wheel of life, revolves. And archaeological sites going back to the very first humans display elaborate caves, opening into the "womb" of the earth, decorated with red ochre and described, in the polite jargon of academic texts, as being representations of "that opening through which we all enter the world."