In The Erotic Mind (1996), Jack Morin, PhD, interviewed hundreds of his sex therapy clients, trying to understand the common elements of peak sexual experiences. From straight, gay, and bi, vanilla to kinky, cis, trans and everyone else, he found what made any fantasy or scene truly exciting was the tension between desire and obstacle.

Desire + Obstacle = Excitement

In vanilla sex, we might find the process of seduction makes the prize more thrilling. Cultural taboos or sexual hangups provide additional obstacles that can add excitement. Making out in the back of your parent’s car was extra thrilling because it was forbidden. For some people, sex before marriage is naughty enough. As long as you find just the right power balance between the forces, you generate pleasure. This mechanism works like a hydroelectric dam: Pressure builds up behind the obstacle, turns the turbines, and creates energy. Similarly, the erotic imagination incorporates narratives of pressure and resistance to generate sexual energy. Individuals have their own personal “sweet spot” where the tension hits just the right level to charge up their excitement. Morin’s equation works on many levels. Lingerie is more erotic than bare breasts because it forms a barrier to the desired body part. If the bra is tight, the body part strains against it and threatens to pop out. If the briefs are small, the engorged penis presses against the fabric, threatening to rip through the obstacle. The tension adds to the interest. In the same way, for a foot fetishist, looking at a foot encased tightly in a beautiful shoe, or a watching bare foot press against the resisting gas pedal is the ultimate thrill.

Pressure + Resistance = Excitement

My variant on the Erotic Equation is based on my interviews with many hundreds of people with niche kinks and my observations of the structure of erotic narratives. If you reduce almost any erotic fantasy down to its most basic structure, at its center is a simple mechanism of pressure and resistance, tension and release. In the world of kink, this equation can be found on every level of the fantasy, from arousal via physical pressure to the tension between one’s fantasies and cultural taboos. In sexual fantasy and sexual play this pressure may be physical, such as tight embraces, tight clothing, trampling underfoot or pushing a gas pedal. It may be interpersonal pressure, such as seduction, dominance and submission. Or it may be social pressure, like sexual taboos and our resistance to them. I invite you to discover the Erotic Equation as it applies throughout this site.