Sheviis, Chapter 4, Mishnah 9. In the two previous mishnayos we learned the principle that one must wait before eating sheviis produce until it has properly ripened, and we noted that with certain types of fruit - figs and grapes - there is an earlier stage, before they have ripened enough to be brought into the house, at which they are already fit to be eaten in the field.
The next type of fruit that the Mishnah discusses according to this standard is olives.
The stages of ripening of olives:
"Mishe'yachnisu revi'is li'se'ah" - once the olives have ripened to the point that a quarter of a log of oil can be produced from a se'ah of olives (a se'ah contains twenty four log, and a quarter of a log is one ninety sixth of that), that is, once they have reached that measure of oil they are capable of yielding - "potzei'a ve'ochel ba'sadeh" - he cracks them open and eats them. It was customary to crack each olive open in order to soften it and sweeten it somewhat, and to eat it in the field and not in the house. This stage permits eating alone, and not anointing with the oil, since the practice at this stage was only to eat them.
"Hichnisu chatzi log" - once the olives have ripened to the point that half a log of oil can be produced from a se'ah, double the first amount - "koseish ve'sach ba'sadeh" - at this stage he crushes them and rubs the oil on his body, in the field and not in the house.
"Hichnisu shelish" - there are two explanations of this stage: (a) once the olives have grown to a third of their full growth; (b) even if they have not grown a third of their growth, one can produce from them a third of the amount of oil they would yield at full ripeness. Once they have reached this stage - "koseish ba'sadeh ve'chones le'toch beiso" - it is worth noting that the words "in the field" here are not meant precisely: at this stage he may bring them directly into his house.
The Mishnah continues: "Ve'chein ka'yotzei ba'hen bi'she'ar shenei shavua chayav be'ma'asros" - at this final stage of a third of their growth, in the other years of the seven year cycle as well, the years that are not the shemittah year and in which the obligation to separate tithes applies, the fruit becomes obligated in ma'asros.
The rest of the tree fruits:
The halachos mentioned regarding the field and regarding the earlier stage were stated with respect to figs, grapes and olives. But with all other types of tree fruit, once they reach the time at which the obligation of ma'asros applies to them - the later stage - that is also their stage for the laws of shemittah. With these there is no distinction between the field and outside the field, and everything depends on the time at which they may be brought into the house; therefore the later stage is the stage at which they become obligated in ma'asros.
Elsewhere, in Maseches Ma'asros, the stages of obligation of each and every one of the tree fruits are discussed. Once a fruit reaches those stages of ma'asros, it is permitted to eat it in the seventh year: there is no loss involved, but rather eating in its plain sense - "le'ochlah", in the language of the verse, for the purpose of eating.