It’s strange to think that feelings of love, or empathy, or euphoria might be nothing over and above states of your brain: that the right neural networks, when spurred into action by the right neurotransmitters, just are those emotions. After all, feeling amorous or affectionate doesn’t at all seem the same sort of thing as being "a pack of neurons," as DNA co-discoverer Francis Crick once put it. Yet the resurgence of MDMA, the drug popularly known as ecstasy, is a compelling illustration of how the neural basis for affection can be exploited as a short cut to intimacy.

Take MDMA, and sure enough, you’re going to want to touch and be touched - a lot. You might find yourself confiding your most secret thoughts to the stranger next to you, since suddenly it seems right, indeed inevitable, that your souls should merge. Wherever you are and whatever you’re doing, sights and sounds and words take on a special intensity and significance. There’s no any longer any question: This Is It - the spiritual, psychic and physical communion that you’ve been yearning for. You’ve transcended the boundaries of self and left petty insecurities behind.

Of course all these pleasurable and profound feelings are absolutely, undeniably real, as real as your brain as it responds to the flood of serotonin made available by the drug. But, it might be asked, since they are radically indiscriminate, are they at all appropriate? MDMA can act like Cupid’s arrow, priming its victim to fall for whatever’s in the vicinity, be it the human equivalent of a coat rack or codfish. As a journalist for the San Francisco Examiner wrote recently, MDMA can even make bad television a memorable experience.

This, I submit, should give pause to anyone wanting to join the ecstasy bandwagon. The feeling that something really matters to us, or is attractive or beautiful or loveable, is best reserved for those things and people that have earned our affections. When the effects of MDMA wear off, we might discover that we revealed ourselves too easily, that there wasn’t any intrinsic quality or virtue to what we were enamored of. We were just on drugs.

So even though feelings of love and affection may turn out to be brain states (according to artificial intelligence guru Ray Kurzweil, someday even robots will be capable of such feelings) it’s still important that the objects of our affections be worthy and durable. Using drugs to generate such emotions may stunt our talent for forging authentic commitments, and as profound as the experience might be at the time, in the long run drugs can’t substitute for a real, if imperfect, lover that exists outside our heads.

Of course, all this will sound like mere moralizing to those who don’t care a fig about the source of good feelings, or their permanence. After all, the primal rave experience, held under the banner of PLUR (Peace, Love, Unity, and Respect) and often enhanced by MDMA and other drugs, is about the moment, not the future. Who’s to say that such moments aren’t worthy and authentic, just because they’re transient? Some therapists argue as well that MDMA can serve as an effective adjunct in treating psychological disorders. With proper guidance, chemically-induced catharsis can lead to insights that carry over into ordinary life, without needing to repeat the experience.

But even accepting such arguments, there are still good reasons to be wary of recreational MDMA use. It is commonly admitted by most users, for instance, that the first time is the best: try it again, and you don’t get quite the feeling. This is a sure sign that the brain has changed in response to just one exposure. The "Tuesday blues," a midweek drop in mood following an ecstasy weekend, is also frequently reported, suggesting that there’s an immediate neural-emotional debt to be paid for the sudden release of so much serotonin. Although more research needs to be done to determine the extent of its neurotoxicity, those familiar with the rave scene acknowledge that heavy ecstasy users seem more prone to depression.

So while it’s highly unlikely that a little ecstasy will kill you (only a few deaths nationwide have been directly attributed to MDMA), it’s possible that repeated use will modify brain function in ways that could compromise cognition and emotional stability. For the past decade a natural experiment on the effects of ecstasy has been underway in Great Britain, where the drug has been endemic in clubs and raves. If regular MDMA use does indeed have significant negative effects, they are likely to show up in British mental health statistics in the next few years.

Those who imagine, dualistically, that they somehow exist over and above their brains are arguably the most at risk of abusing, in the quest for new highs, this most amazing organ of personal identity. Unfortunately this includes many teenagers, who believe not only that they are immortal, but that repeated drinking binges and drug trips somehow won’t affect their developing cognitive resources. A good dose of scientifically grounded monism in health class – teaching that mind and brain are essentially one – might help to curtail enthusiasm for this latest new drug, as well as all the old standbys still available. MDMA isn’t just changing your brain, it’s changing you, and in a way that might not be particularly enjoyable in the long run.

The intuition of mind-body duality is tough to surrender, rooted as it is in the Western philosophical tradition of Descartes, for whom the true self was incorporeal and therefore well insulated from changes in mere matter. But the effects of MDMA show unequivocally that, as far as thinking and feeling goes, "brains are us" - it’s neurons or nothing. So it’s best not to fiddle too much or too carelessly with the organic machinery in our heads, since that’s what we persons are, ultimately. And we’re better off looking for intimacy with a minimum of chemical assistance, for only then can we be reasonably sure it’s for real.