The composer of this song, now thought of as part of the folk tradition, was Velvl Barzher, one of the Brody singers. The Wikipedia entry about him (Velvel Zbarjer) is well worth reading.
Theodore Bikel sang this song on his first LP of Yiddish songs and his version is classic. He has a wonderful orchestra with him. I just banged it out on the piano - you can probably hear that it's raining while I'm doing this...
The song mocks both the credulous Chasid (comparing his rebbe's miraculous abilities to the puny accomplishments of science) and boastful modern man.
Translation from the Yiddish:
Come here to the rabbi's table and learn wisdom.
You thought up the steamboat and take pride in it;
the rabbi spreads out his kerchief and crosses the ocean.
You invented the train and think you're a keen fellow.
The rabbi dallies, he laughs, he doesn't need it at all.
Do you know, then, what the rabbi does while he sits in solitude?
In one minute he flies to heaven and eats his Sabbath meal there.