“R.Isaac further said: Blessing is only possible in things hidden from sight… In the school of R. Ishmael it was taught: Blessing is only possible in things not under the direct control of the eye.”
—bt. Ta’anit 8b
This saying from the Babylonian Talmud is often quoted when trying to understand the phenomenon of coin deposits in synagogues and other Jewish buildings. The expression, explicitly mentioning the control of the eye, can be interpreted as referring to the evil eye, a concept known from Rabbinic literature. In the Mishnah, the Talmuds, and the Midrashim, the usual terms to denote the evil eye are ‘ayn ha-ra’, or “the eye of evil.” Sometimes, however, the word “eye” (‘ayin or ‘eyna) is used without an adjective referring to evil. For the rabbis, “eye” was a descriptive term derived from the physical eye’s power to see, perceive, stare, and explore a variety of psychological and physical appearances: its meaning ranges from the emotions which cause it, to the harm it produces. Furthermore, the eye’s power is a reflection of and reaction to the human eye or the eye of God. Some rabbinic sources claim that the evil eye is a major cause of sickness and death; according to the Talmud, the Angel of Death has eyes everywhere. The opposite of the evil eye is the good eye, or “benign,” “beautiful,” or “nice” eye, which expresses the positive aspects of the eye characteristic of human beings. Thus, people can have a good eye or a bad eye, depending on if they follow the commandments or not. For example, Moses had a good eye when he shared the Torah with the people of Israel (Bamidbar Rabbah 21:15).
Interestingly, the good and bad eyes are also connected to tithing and charity. According to Midrash, a person who gives the most for the terumah has a good eye. Officially, one is not required to be generous with the heave-offering, but one who does has a good eye:
“You shall offer up a terumah unto the Lord (Num 15:21). [Why this repetition?] Because the previous words “you shall offer up a cake for a terumah (Num 15:20) does not specify the quantity, therefore it is written here: You shall give a terumah to the Lord (Num 15:21), which means that it must be such an amount that it could be called a gift to the priest. From this, we can deduce the rule that the minimum which a private individual has to give as a terumah is a 24th part of the whole; and for the public baker it should be a 48th part, because a man’s eye is good and a woman’s eye is bad. Therefore, the minimum which is described for her is a 48th part.” (Sifre Bemidbar 15:21/110, p. 115) 
Thus, when it comes to priestly gifts, anything that is sanctified or given to God can be given with a good or bad eye; but one who gives generously is said to have a good eye. The same is true of tzedakah. According to the Mishnah:
“There are four types of donors to charity: One who gives and does not want others to give – his eye is evil; one who does others to give, but will not give himself – his eye is evil upon himself; one who gives and wants others to give is saintly; one who will not give and does not want others to give is wicked.” (m. Avot 5:13)
In the Palestinian Talmud another story is told:
“A disciple of Rabbi had two hundred zuz less than a dinar. Rabbi was accustomed to give over to him the poor tithe every third year. Once the disciples used an evil eye against the [poor] disciple by making up [the dinar, so that he was no longer short two hundred zuz and could not receive the maaser ani]. Rabbi came and wanted to hand over the poor tithe as he had been accustomed to do. He said to him: “Rabbi, I have the required amount of money.” He [Rabbi] said: “In the case of this one, the blows of the over pious have smitten him.” He instructed his disciples and took him to a tavern and made him one qarat poorer. Then Rabbi handed the poor tithe over to him as he had been accustomed to.” (pt. Sotah 3, 19a)
In other words, charity and tithing, and money in general, were often connected to the concept of “the eye.” Giving, donating, and sacrificing in abundance helped to divert the evil eye. But acting immorally attracted the evil eye. In the story of the Babylonian Talmud, not only do the disciples deprive their fellow citizen from receiving aid, they affect their master’s ability to perform a commandment in the way he was used to.
 For example, Meshorer 1976, p. 112; Ilan 1989a, pp. 27–28.
 Of course, ancient Jews were not the only ones to believe in the evil eye; it was a concept that was well–known across the Greco–Roman and early Christian worlds. See, for example, Dickie 1995; Trzcionka 2007, pp. 101–120.
 Ulmer 1994, p. 4.
 Ulmer 1994, pp. 4–5.
 bt. Avodah Zarah 20b, pt. Sanhedrin 10, 28a. Belief in the evil eye may seem enigmatic to some modern readers, but it was an accepted and widespread part of ancient Judaism. For introductions to Jewish conceptions around magic see: Bohak 2008, pp. 8–69; Harari 2019.
 Ulmer 1994, p. 33.
 “טוֹב עַיִן הוּא יְבֹרָךְ”. To be fair, Bamidbar Rabbah is a late source (dated to after 800 CE), and not part of what we generally label “classical rabbinics.”
 It seems from this text that women always have a bad eye but that is not the case: b. Betsah 29a, states that the good eye of women permits them the right to measure flour, even on a festival day. This shows that the rules concerning good and evil eyes are more complicated than one might think at first.
 For example, עין בעין means “equally.” So, a good eye or a bad eye is how generously you weigh what you sell or give. The connection between this term and the evil eye as an entity that can cause havoc deserves further consideration. For other examples, see bt. Kettubot 100a, bt. Menahot 108b.
 See also Pirke Avot 5:16; bt. Sotah 9a, 38b; bt. Taanit 21a, pt. Pe’ah 8, 21b.
 I am aware that I am utilizing Tannaitic and Amoraic as well as other rabbinic sources to make my case. Since, however, the phenomenon of floor deposits only started in the late 5th century (see below), I decided to look at all writings from during and before this period to assess the rabbinic views on the evil eye, magic, and tithing. It would be useful, however, if scholars of rabbinic literature could tease out a more detailed timeline of rabbinic conceptions around these topics.
 Because of this, he was eligible to receive the poor tithing or maasar ani.
 Since Rabbi was reputed to be very wealthy, his poor tithe would likely have equaled a considerable sum. The portion that Rabbi gave to his student could conceivably have supported that man until the next year of the poor tithe. Rabbi’s largesse toward this individual could explain why some of his peers cast the evil eye on that beneficiary by handing him the single zuz that rendered him ineligible (Wilfand 2015, pp. 57–58; Ulmer 1994, pp. 54–55).
 On the poor tithe, see also Gardner 2015; Wilfand 2014; 2015.