Sean is waiting for a bus when another man joins him at the bus stop. After 20 minutes of waiting, Sean takes out a sandwich from his lunch box and starts to eat. Noticing the other man watching, Sean asks, "Would you like one? My wife made me plenty."
"Thank you very much, but I must decline your kind offer," says the other man,
"I'm Rabbi Levy."
"Nice to meet you, Rabbi," says Sean, "But my sandwiches are alright for you to eat. They only contain cheese. There's no meat in them."
"That's very kind of you," says Rabbi Levy, "but today we are celebrating Passover. It would be a great sin to eat a sandwich because during the 8 days of Passover, we cannot eat bread. In fact it would be a sin comparable to the sin of adultery."
"Really?" Sean asks. "Comparable to adultery? That's hard to believe."
"It's true," replies the Rabbi.
Several days later, Sean and Rabbi Levy meet again. "Do you remember, Rabbi, that when we last met, I offered you a sandwich which you refused because you said eating bread on Passover would be as great a sin as that of adultery?" Sean asks.
"Yes," Rabbi Levy replies, "I remember saying that."
"Well, Rabbi," says Sean, "that day, I went over to my mistress' apartment and told her what you said. We then tried out both sins, but I must admit, we just couldn't see the comparison!"