To call a seisiún a jam is akin to calling a Guinness a beer and leaving it at that. There's just so much more to it. Twice a week, the mandolins, fiddles, dulcimers, tin whistles, singers, and even the set of pipes come out to play for a packed house of punters (that'd be you and me, the listening and drinking public). Anywhere from a handful to dozens of the Bay Area's best Celtic musicians gather to rip through old favorites, as well as attempt complex Celtic melodies for which silence is called — and granted — throughout the bar. It's said a good seisiún feeds the soul. Alternating folk favorites with pulls of the best Guinness in the city, it's hard to argue.