Rambam - 1 Chapter a Day

See the parallels in Chapters 4 and 8 above.
In his Commentary to the Mishnah (Keilim.4:4), the Rambam explains that there are certain tasks performed with earthenware containers after they are fired in a kiln, e.g., they are filed down and smoothed. Nevertheless, these are considered as secondary activities. Overall, once the containers are fired, the task of fashioning them has been completed.

An oven is generally not fired in a kiln. Instead, its clay becomes fired when it is used to bake for the first time.
Since donuts are made from light dough, an oven need not be heated to the same degree to bake them as is necessary if it were being used to bake bread or other heavier substances. Nevertheless, it must be emphasized that when an oven had not been used before, its walls will absorb and let through some heat and therefore, even to bake doughnuts, it requires more heat [the Rambam's Commentary to the Mishnah (Keilim 4:4)].

This applies when the frying pan has already been heated. If the frying pan had not been heated, great heat would be required to warm it (ibid.:2).

Sometimes, it is used as a range upon which to cook and sometimes, its opening is covered and it is used like an oven (ibid.).

As mentioned previously, in the Talmudic era, ovens were often a clay structure built on the ground with its earth as its base. At times, they were built in stages, one level added on to an existing level. Here, the Rambam is speaking about building the initial level of the oven.

I.e., even though one has not built it to its ultimate height, it is still useful and therefore considered a utensil if it is built to this extent.

Although the mishnah (Keilim 5:1) uses the expression “even the slightest amount,” Chulin 124a explains that the intent is a handbreadth.

Since it is used for cooking, not for baking, it does not require as much heat as an oven and, hence, need not be as large.

I.e., instead of the oven being heated from its inside, it was subjected to heat from the outside.

Without any food having been placed inside of it [the Rambam’s Commentary to the Mishnah (Keilim 5:4)].

Although the mishnah (ibid.) mentions the ruling in the name of Rabban Gamliel alone, the Rambam understands it to have been accepted by the other Sages as well.

Flax is naturally dark and becomes whitened when heated.

Flax only requires a small amount of heat to whiten. Indeed, if one would apply excessive heat, it would be ruined.

To the extent that it became susceptible to ritual impurity.

Which impart impurity only due to Rabbinic decree.

The Ma’aseh Rokeiach differentiates between this ruling and that of Chapter 14, Halachah 7, which states that even when an earthenware container is divided by a partition, it is considered as a single entity, explaining that there, the entire container had already been made susceptible to impurity, while that was not the case in this instance. Alternatively, it is not common to divide an earthenware vessel, but it is common to divide an oven.

And thus became susceptible to impurity.

I.e., the half that is next to it.

The Ra’avad had a different version of the Tosefta than the Rambam and therefore differs with his ruling. The Kessel Mishneh justifies the Rambam’s decision.

As stated in Chapter 1, Halachah 6, stone keilim are not susceptible to ritual impurity.

I.e., as the Rambam proceeds to explain, the specific laws that apply to earthenware ovens do not apply it.

I.e., an earthenware container and not a metal one.

Generally, an article attached to the ground does not contract impurity like the ground itself. Nevertheless, an exception is made with regard to an oven, because the Torah itself states that it contracts impurity.

All of the above laws apply with regard to metal keilim, but not earthenware ones.

Our translation is based on the Rambam’s Commentary to the Mishnah (Keilim 5:11).

Since the clay patch or addition improves its functionality, it is considered as an earthenware container.

Otherwise, the hole is insignificant and therefore, the clay patch is also of no consequence.

In particular, this applies to the size of a hole patched with clay. If fire emerged before it was patched, the clay patch causes it to become susceptible to impurity as an earthenware container (ibid.).

For the pot-rests are a useful addition (ibid.).

It is not susceptible to the impurity associated with an earthenware container. Instead, it is considered as a metal k'li.
In this instance, the addition is not significant, because unlike an oven for which the insulation would be useful, for a range it is of no avail. For the cooking on a range is done by placing a pot over the holes and the heat generated by the fire is sufficient for that purpose, even without the added insulation (ibid. 5:11).

As mentioned in Halachah 2, in the Talmudic era, the ovens were often structures with no base. As such, if an oven was not attached to the ground, one might think that since it is not functional, it is not susceptible to impurity.

Significantly, both here and in his Commentary to the Mishnah (Keilim 5:6), the Rambam does not cite the same phrase from the prooftext as his source, Shabbat 125a.

Once an oven has been heated and its preparation is thus completed (see Halachah 1), it is susceptible to impurity no matter where it is located (see ibid.).

The commentaries to Keilim 8:9, the Rambam’s source, emphasize that we are speaking about an instance where the place to rest a pot was made from clay. It appears, however, that the Rambam followed a different version of that mishnah and he would not necessarily agree to the above point.

Even though the furnace would be primarily used for smelting, since part of its structure is a place for a pot, it can also be considered as a range.

Lime is produced by crushing stone and then burning it at high temperatures in a furnace.

In the range of glassmakers mentioned in the previous halachah, the sand from which glass was made fired into a block of glass. In the furnace mentioned in this halachah, the block of glass would be melted so that it would be pliable and able to be shaped into utensils (Tifferet Yisrael, Keilim, op. cit.).

These furnaces would be made of brick and not coated with clay. Hence, they were not considered as earthenware vessels (Tifferet Yisrael, Keilim, 8:9).

Made from clay.

I.e., only if it has a border is it impure. In his Commentary to the Mishnah (Keilim, op. cit.), Rav Ovadiah of Bartenura explains that these were large ovens that were considered as connected to the ground and hence pure. The border, however, is considered as an earthenware container and causes the entire oven to be susceptible to impurity.

As all earthenware containers do.

If a source of impurity touches its inside.

Rambam LeAm explains that according to Scriptural Law, such an oven is not considered as an earthenware vessel and is not susceptible to ritual impurity. Our Sages, however, were stringent and decreed that it should be considered susceptible to impurity. Nevertheless, in order to make a distinction and prevent terumah and sacrificial foods that contracted impurity as a result of it from being burnt, they ruled that it would impart impurity only through touch. See parallel concepts in the Rambam’s Commentary to the Mishnah (Keilim 5:3).

Even though stone keilim are not susceptible to impurity, these stones are not considered as entities in their own right, but part of the oven and contract impurity with it.

In Chapter 17, Halachah 4, the Rambam defines a tira as a place built at the side of an oven where loaves of bread are placed after they are removed from the oven. There also the relevant laws are stated.

For earth, even when subsidiary to a k’li, never contracts impurity.

From the Rambam's Commentary to the Mishnah (Keilim 5:3), it appears that this refers to a structure near a range where pots are placed so that they will remain hot.

Rambam LeAm states that this applies in a situation where the tira is not connected to the range. It is pure, because the food is not cooked on the tira.

The barrels and the frying pans were placed together in such a manner that they would enclose an area where kindling fuel could be placed and serve as a base on which pots could be placed to cook.

I.e., the inner space between the two barrels.

I.e., the external surface of the barrels and frying pans are susceptible to impurity when touched by impure liquids. (see the parallel in Chapter 13, Halachah 9).

I.e., its purity or impurity is not dependent on the presence of impurity in the inner space of the range.

To the earth (Tifferet Yisrael); alternatively, to each other (Rav Ovadiah of Bartenura). See note 54 below and also Halachah 17.

Since the metal pegs are the primary element of the utensil, they are governed by the laws apply to a metal range described in Halachah 6.

The previous halachah spoke of three stands or pegs, because the stands or pegs are narrow. Stones, by contrast, are wide and even two can serve as a base on which a pot can stand.

Here, also, both interpretations given in note 53 are repeated. Based on Halachah 17, it would appear that the Rambam does not see them as mutually exclusive.

To the earth. In this instance, only this interpretation is appropriate.

I.e., between the oven—or one of the other articles mentioned—and the stone, it is possible to support the pot and enable it to cook.

Because it and the object that is susceptible to impurity are combined.

The commentaries explain that the term translated as “stone” refers to a loose stone, while that translated as “rock” refers to a rock embedded in the earth and attached from the beginning of existence.

Because the object to which the rock is connected is not susceptible to ritual impurity.

Who sells large amount of cooked meat. They would kindle several ranges at a time and cook a pot on each one [Rav Ovadiah of Bartenura (Keilim 6:2)].

So that a fire could be placed under them and together they would support a pot.

Since these are not considered as earthenware vessels according to Scriptural Law and the intent was to use them to cook separate pots, our Sages did not rule stringently. The commentaries point to the laws stated in Chapter 13, Halachah 13, as a source.

Each of the two sets of stones constituted an independent range.

For, as stated in Halachah 14, such a range is susceptible to impurity if it comes into contact with impure liquids.

In his commentary to Keilim 6:3, Tosafot Yom Tov emphasizes that this ruling depends on the conception that in such an instance, the usual practice is to take a stone that is large enough to serve as a base for pots on either side.
On that basis, he differentiates between this law and the law stated in Chapter 13, Halachah 13 (which serves as the source for the previous halachah). For in that situation, it was not common to make the divider large enough to serve each side independently.

In his Commentary to the Mishnah (Keilim 6:3), the Rambam explains that the term has the implication of being placed in a category for all time.

And the other stone.

These portions of the middle stone are impure.

Because the previous situation has not been brought to an end entirely. Both of the external stones are in place and they are still functional.

Because the ranges that became impure are no longer functional, it is as if a new situation has been created.

The ranges are considered as having been newly made. The previous situation is not considered to have been reconstructed.

As stated in Halachah 1 above.

I.e., these — and the stones added later — were all coated with clay [the Rambam’s Commentary to the Mishnah (Keilim 6:4)].

Creating two new ranges.

Like the middle stone described in the previous halachah.

I.e., they are both considered as impure in their entirety.

In his Commentary to the Mishnah (Keilim 7:2), the Rambam explains that this refers to a cubic earthenware structure that functioned as a serving table. Its upper surface had receptacles in which a mixture of ash and coals were placed and upon which food was placed to warm and/or to remain hot.

Because it is not used to cook upon.

Thus the laws applying to it are more lenient in two aspects, as the Rambam proceeds to explain.

Once a k’li is permanently attached to the ground or to a building attached to the ground, it is no longer considered as a k’li, but as part of the entity to which it is attached. Hence, is not susceptible to impurity.

I.e., both leniencies. Even if it is attached to the ground, it is susceptible to impurity. Similarly, even if it has a hole, as long as it still can be used to cook, it is susceptible to impurity (ibid.).

Instead, the counter is considered merely like a receptacle. It is not considered like a yad, a handle, of the oven.

I.e., the part of the countertop that is left flat, without holes for food to warm.

The Mishnah Achronah states that this applies to the basket. The range built above, by contrast, is bound by all the laws applying to a range.