It is known that one of the most far-reaching rabbinical decrees pertaining to Shabbos is the prohibition of picking up/carrying article which are defined as מוקצה (set apart from use on shabbos.)
Items which are appropriate and have been set aside, either specifically, or by default, for use on shabbos may be handled within a רשות היחיד (private domain.)
However, anything defined as מוקצה on shabbos may not even be handled within such an area.
There are various opinions offered as to the reason for this prohibition, but that will be left for a possible future post.
On our daf, we see a number of categories of Muktza, and a number of different reasons for moving Muktza, some of which might be permitted for some of these categories but not for others.
The three main categories that we see on this daf are as follows:
דבר שמלאכתו להתיר – A vessel normally used for an action which is permitted on Shabbos.  Although this is not really a category of Muktza per se, our daf does make reference to the stringent view of Rabbi Nechemya that even such a vessel may only be handled when needed for its permitted purpose, not when there is no such reason for doing so.
כלי שמלאכתו לאסור  – a vessel normally used for a melacha which is prohibited on Shabbos
דבר שמקפיד עליו  -something of
value one looks after extra carefully.
 (this is also referred to  as מוקצה מחמת חסרון כיס- see Shabbos 157a)

There are also a number of reasons that one might move a muktza item, each with their own set rules:
שלא לצורך כלל  – for no particular constructive reason
מחמה לצל – in order to protect it  (literally moving it from the sun into the shade)
לצורך גופו  – when one wishes to use the item itself for a permitted purpose.
לצורך מקומו – for the sake of its place- when one needs the space it is occupying for a permitted purpose  (provided that space is not defined as a בסיס לדבר האסור [base for a forbidden item], a different topic.)
The Mishna on 122b lists a number of items that may be used for various purposes on Shabbos, despite the laws of Muktza.
 
One of them is a hammer, which may be used for cracking nuts.
There is a dispute in the Gemara between Rav Yehuda and Rabbah regarding what type of hammer is referred to in the Mishna.
Rav Yehuda claims that it is referring to a hammer usually used for cracking nuts, which is a כלי שמלאכתו להתיר and thus may be used, at least for its intended permitted purpose.
Rabbah points out that our same Mishna permits using a winnowing shovel or pitchfork to pass food to a child on, and these instruments are only made and bought for performing forbidden melachot with them.
As such, Rabbah concludes that the hammer referred to in the Mishna could even be a smith’s hammer, which is clearly a כלי שמלאכתו לאסור.
We conclude from there that it is permitted to use a כלי שמלאכתו לאסור for a permitted purpose!
The Gemara a little later brings a Beraita to question this leniency.
Beis Hillel and Beis Shamai argue whether it is permitted to use an עלי (evidently a type of important vessel) to cut meat for the sake of Simchas Yom Tov.
Yet both agree that once the meat has been cut, it may no longer be used for another permitted purpose.
This seems to imply that in the absence of the special leniency of simchas Yom Tov, using something normally used for a forbidden purpose is forbidden even when one uses it for a permitted purpose, against Rabbah’s conclusion.
The Gemara answers that this instrument is different, as it is more like סיכי זיירי ומזורי (which Rashi identifies as specialist tools used by painters, or alternatively specialty weaving tools), which a person takes pains to look after and sets aside a special place to store. (see also Tosfos who quotes the Aruch’s translation(one of the most important  linguists amongst the Rishonim).
It follows that special instruments of value that a person is particular to look after and store in one place are treated as a more serious form of מוקצה and may not be used even for a permitted purpose.
The Gemara further records a debate between Rabbi Chiya bar Abaya quoting Rabbi Yochanan and Rav Shemen bar Ada regarding what type of hammer the Mishna permits one to use.
Whereas both agree that a hammer used for beating gold may be used for permitted purposes, even though it is a דבר שמלאכתו לאסור, Rabbi Yochanan is of the view that a hammer used for pounding spices (the forbidden melacha of grinding) may not be used even for  a permitted purpose, seeing as a person is particular about it.
Yet the primary source for the prohibition of using מידי דקפיד עליו (something one is particular about), can be found in the second Mishna on amud bet.
There, Rabbi Yossi tells us that any vessel may be used for a permitted purpose on shabbos, with the exception of a large saw and the peg (blade) of a plough, presumably because they are  particularly valuable or fragile items that the owner is particular to look after.
The Gemara seems to understand that Rabbi Yossi is not referring to these 2 items only, but uses them as examples of anything that fits into the category of things used for a specialised purpose that the owner takes great care with.
We thus have 3 primary sources for the stringency applied to items that one is particular with:
1.      The Beraisa where Beit Hillel agrees that an עלי many only be used until the meat has been cut, and the Gemara’s understanding that this is similar to the special painter’s tools (as explained by Rashi.)
2.      The view of Rabbi Yochanan, disputed by Rav Shemen bar Ada, that a hammer used for spices may not be used on shabbos at all.
3.      The Mishna (as interpreted by the Gemara) which permits using any vessels on shabbos except those that one is particular about.
 
At first glance, these 3 sources all seem to be saying the same thing, to the point that we need to understand
1.      Why the Gemara brought the Beraisa to query the lenient ruling of Rabbah rather than an explicit Mishna
2.      How Rav Shemen bar Ada could disagree with an explicit Beraisa AND Mishna.
 
Yet, when one looks more carefully, it appears that there are different categories of things one is particular about, and Rashi actually seems to define them differently.
There are things which one is so particular about that one usually  does not allow them to be used for anything but their intended professional purpose.- this seems to be the category discussed in the Mishna, which everyone agrees may not be used at all on Shabbos.
There are things which one might allow to be used for another purpose, but which one is careful enough to keep in a special place while not being used- This is the case discussed in the Beraisa.
Then, there are things which one might not be particular enough about to dedicate a special place for, but which one does not use for other purposesד in case they get dirty or disgusting, such as the hammer used for pounding spices (see Rashi who makes this point  and the Ritva who has a different version of the Gemara and holds that one is more particular about a gold hammer than a spice hammer.)
Perhaps, this is what Rabbi Yochanan and Rav Shemen argue about- the both agree accept the basic stringency of דבר שמקפיד עליו , but differ as to the extent of its application.
This is just an initial analysis, and a study of the Rishonim will reveal that it is not so straight forward and there are many ways to approach this, but that’s it for today….
These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha.