You must strive for a continuous awareness of the glimpse of samadhi in coitus. One should try to grasp that point, that glimpse of samadhi which flashes like lightning in the midst of intercourse, which shimmers for a second like a will-o’-the-wisp and then vanishes. Your effort must be to know it, to become acquainted with it, to hold to it. If you can make the contact fully, even once, in that moment you will know that you are not a body, that you are bodiless. For that fraction of time you are not a body; in that moment you are transformed into something else: the body is left behind and you become the soul, your real self. If you have a glimpse of that glory even once, you can pursue it, through dhyana, through meditation, to establish a deep and lasting relationship with it. Then the path to samadhi is yours. And when it becomes part of your understanding, part of your knowledge and of your life, there will be no more room for lust.
To reach celibacy sex must be understood. To know sex is to be free of it, to transcend it; but even after a lifetime of sexual experience, a man is not able to detect that intercourse gives him a fleeting experience of samadhi, a peek into superconsciousness. That is the great pull of sex; that is the great allure of sex: it is the magnetic attraction of the Supreme. You have to know and to meditate upon this momentary glimpse; you have to focus on it with awareness. On everyone its pull is so tremendously strong.
There are other, easier ways to attain to the very same experience—meditation, yoga and prayer are other alternatives—but only the channel of sex has such a powerful influence on man. It is very important to consider the various ways there are to reach the same goal.
Excerpts taken from Osho Books – The Last Testament vol 4 chapter 20, From Sex to Superconsciousness chapters 2,4,5