We are studying Maseches Menachos, chapter eight, mishnah one. The chapter deals with the flour, oil and wine used for menachos (meal offerings). The mishnah teaches: "Kol korbanos ha'tzibbur veha'yachid ba'in min ha'aretz umi'chutzah la'aretz, min he'chadash umin ha'yashan" - all menachos, whether communal menachos or those of an individual, are valid when brought from flour that originated in Eretz Yisrael or outside of it, whether from the current year's crop (chadash) or from last year's crop (yashan). There are several qualifications to this rule regarding chadash, which we will discuss below.
Two exceptions:
The mishnah continues: "Chutz min ha'omer u'shtei ha'lechem, she'einan ba'in ela min he'chadash umin ha'aretz" - two offerings are excluded from this rule:
The Omer: a barley meal offering brought on the second day of Pesach (which we will discuss at length further on), which comes from the new barley crop.
The Shtei HaLechem: two loaves of wheat flour, which come from the new wheat crop.
Both of them, based on explicit verses, must come specifically from the current year's crop - barley for the Omer and wheat for the Shtei HaLechem - and specifically from produce grown in Eretz Yisrael.
What the Omer permits and what the Shtei HaLechem permit:
Bringing the Omer at the beginning of Pesach is what permits the new year's grain to be eaten by a person. The Shtei HaLechem likewise come to permit the new year's grain - but for the altar. It emerges that the menachos offered between Pesach and Shavuos still come from the previous year's grain, from the yashan and not from the chadash.
The ruling of the Rambam:
Regarding the Omer: one is obligated to use barley from the current year's crop, and one who uses produce that is not from this year has not fulfilled the mitzvah at all - for the verses are explicit, and this is the very essence of the Omer.
Regarding the Shtei HaLechem: after the fact, if no new wheat is available and he brought from the previous year's wheat, it is valid.
"V'chulan einan ba'in ela min ha'muvchar":
Ideally, all the offerings, whether communal or those of an individual, must come from the finest ingredients - first-grade wheat. And what is the choicest produce?
"Michmas u'Zenocha alfa la'soles" - these two places are the finest sources for producing soles, the fine flour. 'Alfa' - after the first letter of the Greek alphabet, meaning first grade, the choicest of the choice.
"Sheniyah lahem Chafarayim ba'bik'ah" - the second grade in quality, and it too is acceptable even ideally. It is worth noting that there are two places called Chafarayim, and the reference here is only to the one in the valley. This is the preferred source when produce from Michmas and Zenocha cannot be obtained.
"Kol ha'aratzos hayu kesheiros ela mikan hayu mevi'in": - "All lands were valid, but it was from here that they would bring":
Grain from anywhere is valid after the fact; the places listed are simply the preferred sources to begin with. And when the Mishnah says that all lands are valid, this includes even outside Eretz Yisrael - one may bring grain that grew outside the Land. Yet we have to remember that the Sages decreed tumah upon the lands of the nations, and one may not use impure ingredients for the offerings.
Perforce, then, we are speaking of grain brought from outside the Land in a state in which it had not yet become susceptible to tumah. Raw barley kernels that were never wetted - and which one would rather not have wetted, lest they grow moldy - are entirely pure even while sitting outside the Land. Even if a dead mouse were lying on them, they remain in their purity, since tumah does not take hold on food until it has been made susceptible through moisture.
That is the situation in our case as well: we are dealing with wheat that was never wetted and never became susceptible to tumah, and therefore it is valid even when it came from outside the Land. But once it has already become susceptible and has begun to be able to receive tumah, we must assume that all of it is impure, since the very soil outside the Land is impure.
In summary: In this Mishnah we learned that all communal and individual offerings come from the Land and from outside it, from the new crop and from the old, except for the Omer and the Two Loaves, which come specifically from the new crop and from the Land; we saw the role of the Omer and the Two Loaves in permitting the new grain to a person and to the Altar, the ruling of the Rambam after the fact, the law of "from the choicest" and the superior locations for fine flour, and the conditions of purity that allow grain to be brought from outside the Land.