How It Is Done*
There is a description in a child's science book of the act of love that makes it all quite clear and helps when one begins to forget. It starts with affection between a man and a woman. The blood goes to their genitals as they kiss and caress each other, this swelling creates a desire in these parts to be touched further, the man's penis becomes larger and quite stiff and the woman's vagina moist and slippery. The penis can now be pushed into the woman's vagina and the parts move "comfortably and pleasantly" together until the man and woman reach orgasm, "not necessarily at the same time." The article ends, however, with a cautionary emendation of the opening statement about affection: nowadays many people make love, it says, who do not love each other, or even have any affection for each other, and whether or not this is a good thing we do not yet know.
*please do not sue me yet