Why Can't Jews Rip Toilet Paper on the Sabbath?

Why can't Jews rip toilet paper on the Sabbath. Back in PA my Jewish friends would rip up all their toilet paper into sheets on Friday and they told me it's because they weren't "allowed" to rip any paper on the Sabbath. How come?

 

Did they roll up Saturdays blunts on Friday also ?

 

That title sounded like the beginning of a very bad joke.

 

Traditionally in rabbinic Judaism there are 39 melachot which are categories of work forbidden on Shabbos. A long list of prohibited activities are derived from these. melachah is generally understood as creative acts, that is' those things that assert dominion on the world around us. As Heschel put it, it's a day for being instead of doing. The 39 melachot are derived from activities done for the construction of the mishkan which was halted on Shabbos. You can find a list of them here:

http://en.wikipedia.org/wiki/39_categories_of_activity_prohibited_on_Shabbat

and here:

http://www.torahtots.com/torah/39melachot.htm

If they're pre-tearing all of their TP it's probably unlikely they'll light a fire on Shabbos.

Dauer