daf bit: Shabbat 43

[cellio]

The mishna teaches: on Shabbat one may not place a vessel under a lamp to catch the oil, but one can place it before Shabbat so long as one does not benefit from the oil. The g'mara (somewhat) clarifies: you can't place the vessel on Shabbat because you can only move a vessel for the sake of its contents and its contents aren't permitted. Why aren't the contents permitted? Because the oil that you'll catch (for reuse) by moving the vessel was already designated for use on Shabbat; you can't reuse it some other time. (42b-43a)

So setting a drip-pan to protect your furniture/carpets is apparently fine (in advance, and if you don't reuse the drippings), but setting a drip-pan to recycle the oil isn't. (The g'mara then goes on to apply this principle to other cases that don't summarize well, including freshly-laid chicken eggs and beehives.)

This is not (only) the principle of muktzeh, items forbidden for use on Shabbat, because the g'mara is saying you can't use the oil any other time. Muktzeh generally applies to things you can't use on Shabbat but can use other times; for example, you aren't allowed to touch your car keys on Shabbat, but you're certainly allowed to use them the rest of the week.

Comments

[dr-zrfq.livejournal.com]

the oil that you'll catch (for reuse) by moving the vessel was already designated for use on Shabbat; you can't reuse it some other time.

Not even on a future Shabbat?

[cellio]

Good question. I don't know, unfortunately.