In her book "Future Sex,'' journalist Emily Witt brilliantly unpacks how and why this kind of engineered connection -- the sleek ability to trespass into the intimate and sexual lives of people you never have to talk to or touch or even know by name (unless you choose to) -- has changed our attitudes about sex, from the sacred to the profane. Bearing titles like "Internet Dating,'' "Live Webcams,'' and "Polyamory,'' these gorgeously written essays, linked by tone, style, and a singular, ambitious purpose, are brimming with intellect and infused with a caustic, compelling humor that marks our most astute and entertaining cultural critics. "Future Sex'' explores sexual predilections that you never thought you'd find interesting ("multiperving" for example, or "mass intimacy," which sounds like a nauseating group cuddle).

Witt arrives in San Francisco disappointed by her life's trajectory. Although she viewed herself as a noncomformist, she arrives at the "future" that she and her friends discussed while simultaneously engaging in "friends with benefits" situations or "committed non-relationships" -- assuming it would culminate in marriage or a "committed love relationship." Yet here she is, single. Flummoxed, inspired, and aware that she is, in fact, experimenting, Witt decides to spend a year breaking every rule she'd once "experienced satisfaction obeying."

And break them she does. She deliberately and self-consciously explores the world of "alternative sex" as well as the ways it is aided and abetted by various innovations. Desire, it turns out, diverges from widely acceptable norms as readily in rural Iowa -- where Witt meets a middle-aged woman who discovered she "liked to guide people through their masturbatory fantasies" -- as it does in the Bay Area, where "[p]olyamory was a neologism one absorbed in San Francisco just by breathing the air."

A lesser writer might have written a stunt memoir in which the narrator is valorized for her chutzpah and willingness to be game. Witt is open and brave and remarkably nonjudgmental, but she roots such personal experiences as "orgasmic meditation," in the philosophical perspectives of Simone de Beauvoir and others. Witt is as fine a literary stylist as Joan Didion, with the same cool, dispassionate gaze that also manages to avoid disinterest. As an essayist she is as rhetorically powerful as Rebecca Solnit.

Witt approaches subjects ranging from Internet dating to the politics of everything from mobile webcams that make live sex available from a fast-food joint on a bleak cross-country highway, to the proliferation of readily available birth control for women.

Advances in technology -- much of it futuristic even 10 years ago -- have not just changed the way we think about sex and our perceived access to it, but how we do it. And this, Witt finds, is where the real confusion lies. There are rules for making a "successful" Internet dating profile (success meaning marriage, not hot sex), rules for "how to keep a man" (for sex and for commitment), but no rules for how to have sex in a way that is guided by pure desire divorced from external pressures or expectations. In this sense, the future has already failed us. "America had a lot of respect for the future of objects," Witt writes, "and less interest in the future of human arrangements. . . . To experience sexuality was to have a body that pursued a feeling, a dot in the distance toward which it must move."

Although "Future Sex'' is squarely focused on the path to discovering authentic sexuality, it is just as much a book about how to be in the world. As Witt clearly illustrates, our feelings and attitudes and actions about sex inescapably tie us to our values, as well as to our fears, our pasts, and yes, our futures.

Up until her 30th year, Witt viewed married life as a "vocation, one way of being in the world." But sometimes, Witt reminds us, we can't choose what we do, or with whom we do it. Future contentment doesn't just arrive like a train arriving in a station, an image she employs several times. Sometimes we have to work for connection, because faced with a range of seemingly endless choices, we still may not be able to find what -- or whom -- we're looking for.