The Torah mandates that produce must be tithed before being eaten. The tithing process involves allocating portions of produce for designated parties or purposes. Produce that has not been properly tithed is termed tevel and is forbidden to all. Eating tevel incurs the heavenly death penalty. The Mishna tells us that in the Second Temple period there was no longer a need to inquire whether produce had been properly tithed (M. Sota 9:10). The Talmud recounts that Yohanan the High Priest did a survey and found that the majority of uneducated people were not fulfilling all the tithing requirements (B. Sota 48a). Indeed the unlearned were scrupulous about separating teruma gedola, the heave-offering awarded to kohanim from an Israelite's produce. They were, however, less meticulous about other tithing obligations. Their care in giving only teruma gedola stemmed from the mistaken impression that one incurred the heavenly death penalty only by eating produce from which teruma gedola had not been separated. Yohanan the High Priest explained: "My children, just as eating teruma gedola is a sin punishable by divinely decreed death, thus eating terumat ma'aser - the heave-offering the Levite must appropriate to the kohen - and tevel is a sin punishable by divinely decreed death." Due to the gravity of this sin, Yohanan the High Priest legislated that all doubtful produce should be tithed and a new category of produce was designated: Demai - produce with unknown status that must be tithed before being eaten. From demai produce, ma'aser rishon - a 10th of the produce after teruma gedola has been separated - must be apportioned to the Levite. While the Levite normally receives the ma'aser rishon, in the case of demai the burden of proof lies with the Levite to show that the produce had indeed been untithed. Until the Levite can produce such proof, the ma'aser rishon remains in the hands of the owner. While it is in the hands of the owner, however, the terumat ma'aser, the heave-offering that the Levite normally gives to the kohen and may not be eaten by non-priests, must be given to the kohen. After ma'aser rishon has been separated, a further 10th is also separated. During the first, second, fourth and fifth years of the seven-year shmita cycle, this second tithe - known as ma'aser sheini - is brought to Jerusalem and eaten there. Alternatively, ma'aser sheini may be redeemed and the money taken to Jerusalem and spent on food in the capital city. During the third and sixth year of the shmita cycle, instead of ma'aser sheini, a tithe for the needy is apportioned - ma'aser ani. As with the Levite claiming a tithe from demai, the needy must prove that the demai produce has previously not be tithed in order to claim ma'aser ani. While demai produce must be tithed before being eaten, the Mishna states an exception to this rule: Demai may be given to the needy or to guests without tithing it first (M. Demai 3:1). The Talmud quotes this Mishna and records a dissenting opinion on the matter (B. Berachot 47a; B. Eruvin 17b; 31a-b): We do not feed the needy or guests with demai. This second opinion is cited in the name of the school of Shammai and is not adopted by normative law. Thus Halacha rules in accordance with the opinion cited in the Mishna - the opinion of the school of Hillel - that demai may be offered to the poor or to guests. The commentators discuss the identity of these guests (achsaniya). According to one opinion the guests are soldiers who are being billeted in people's homes. The responsibility to feed these soldiers falls on the hosts. Since these soldiers are away from their own homes, they are classified as needy, as is anybody who leaves his domain (Rashi, 11th century, France, following M. Pe'a 5:4). Indeed elsewhere our sages teach us that demai is one of four things that soldiers are entirely exempted from during a military campaign, even if there is no danger in tithing demai before consuming it (M. Eruvin 1:10). Thus the Mishna essentially uses two labels for the needy who may be offered demai - the local poor and the visiting foreign legions. Another opinion suggests that achsaniya refers to a different group of people: regular visitors whom we invite into our homes (Maimonides, 12th century, Cairo). Why may demai - normally forbidden - be given to the needy and to guests? We can answer this question in two ways: a legal justification can be offered and the philosophical underpinnings can be explored. From a legal standpoint, the demai decree is a later rabbinic enactment and as such open to other considerations. Because the majority of the unlearned indeed did tithe produce, and because the demai decree of Yohanan the High Priest was only legislated in consideration of a significant minority, the sages relaxed the law in certain cases (Rashi). Probing this exception we can suggest that the sages employed this legal mechanism in a bid to assist those who bear the burden of supporting the needy and to encourage those who host others in their homes. Thus this law reflects the valence of helping the underprivileged and the import of hosting guests (Maimonides). This leads us to perhaps the most striking aspect of the exception to the demai decree, namely, the value system reflected by the permitted uses of demai. Demai, as we said, is produce that we have a genuine doubt as to whether it has been tithed. On the one hand, this suspicion is not dismissed out of hand. The religious severity of eating untithed produce necessitates affirmative action and the produce must be tithed lest it was hitherto tevel. On the other hand, assistance to the needy and hosting others in our homes are paramount values in our tradition. When weighing competing objectives, our sages declared that helping the needy and hosting others override reservations we have about the produce. Our concerns recede in the face of assisting those in need and opening our homes to others. The writer is on the faculty of Pardes Institute of Jewish Studies and is a rabbi in Tzur Hadassah.