The downside to life is that it comes with a neverending onslaught of nonsense and senselessness, tragedy and inconvenience, violence and frustration and sickness and stupidity, plagues and pains and problems that bubble and fester and grow as we lurch toward our one true outcome. The upside is Led Zeppelin.

My gripe for today is mundane: I need to get an MRI every few months, and I hate MRIs. It seems, ironically, that they are in my case perfectly tailored to upsetting the symptoms of the condition they’re being used to monitor, as the tense quarters and frequent vibrations seem to freak out my neck, back and arms.

A few years ago, the MRI that ultimately diagnosed my M.S. rendered my entire left arm spasmodic and numb for a couple of hours. Too stupid or prideful to say anything to the people at the MRI place, I had to untuck my shirt and leave the place with my pants belted on but unbuttoned and unzipped because I could not control my left arm enough to fasten either. I staggered in shock to the Columbus Circle mall and sat at a table in the Borders on the second floor until it passed, terrified. It sucked, needless to say.

You know what doesn’t suck? That’s right: Led Zeppelin. At the MRI place today, for the first time, they offered headphones and asked me what type of music I like. I asked what my options were, and they said it was Pandora so I could pick whatever I wanted.

I’m not a huge Zeppelin guy or anything. I only own one of their albums, plus a CD full of their hits that I downloaded my freshman year of college during peak-Napster. But I recognize that they’re awesome, and under pressure of the waiting technicians I didn’t want to pick anything too obscure or too pretentious so I just blurted out, “Zeppelin. Led Zeppelin.” So they played Zeppelin, and Cream and Pink Floyd and the Rolling Stones, and it was hard to imagine anyplace I’d rather be than crammed inside the MRI tube. When George Thorogood came on I thought about squeezing the little emergency button for help, but I stuck it out.

How can music possibly be so awesome? How does it exert so much power over our moods? Is there anything else so abstract that we appreciate so regularly? To what evolutionary advantage did we become emotionally susceptible to series of percussive and pitched sounds strung together?

Who cares?