He is popularly known as the author of two sayings: "If I am not for myself, who will be for me? And when I am for myself, what am 'I'? And if not now, when? and the expression of the ethic of reciprocity, or "Golden Rule": "That which is hateful to you, do not do to your fellow. That is the whole Torah; the rest is the explanation; go and learn.
Hillel lived in Jerusalem during the time of King Herod and the Roman Emperor Augustus. In the Midrash compilation Sifre (Deut. 357) the periods of Hillel's life are made parallel to those in the life of Moses. Both lived 120 years; at the age of forty Hillel went to the Land of Israel; forty years he spent in study; and the last third of his life he was the spiritual head of the Jewish people. A biographical sketch can be constructed; that Hillel went to Jerusalem in the prime of his life and attained a great age. His activity of forty years likely covered the period of 30 BCE to 10 CE.
When Josephus ("Vita," § 38) speaks of Hillel's great-grandson, Rabban Shimon ben Gamliel I, as belonging to a very celebrated family (γένους σφόδρα λαμπροῦ); he probably refers to the glory which the family owed to the activity of Hillel and Rabban Gamliel Hazaken. Only Hillel's brother Shebna is mentioned; he was a merchant, whereas Hillel devoted himself to studying the Torah whilst also working as a woodcutter (Hertz 1936).
Whatever Hillel's position, his authority was sufficient to introduce those decrees which were handed down in his name. The most famous of his enactments was the Pruzbul, (προσβολή), an institution which, in spite of the law concerning cancellation of debts in the Sabbatical year (Deut. xv) ensured the repayment of loans. The motive for this institution was the "repair of the world", i.e., of the social order, because this legal innovation protected both the creditor against the loss of his property, and the needy against being refused the loan of money for fear of loss. A likewise tendency is found in another of Hillel's institutions, having reference to the sale of houses. These two are the only institutions handed down in Hillel's name, although the words which introduce the pruzbul show that there were others. Hillel's judicial activity may be inferred from the decision by which he confirmed the legitimacy of some Alexandrians whose origin was disputed, by interpreting the marriage document (ketubah) of their mother in her favor (Tosef., Ket. iv 9; B. M. 104a). Of other official acts no mention is found in the sources.
In the memory of posterity Hillel lived, on the one hand, as the scholar who made the whole contents of the traditional law his own (Soferim xvi. 9), who, in opposition to his Judaean colleague, Shammai, generally advocated milder interpretations of Halakha (Jewish law and tradition) and whose disciples stood in like opposition to Shammai's disciples. It was in this time that the rabbinical tradition was recorded, with Hillel as its 'founder'. Modern-day Rabbinic tradition descends from this the law that Hillel recorded.
He was known as the saint and the sage who in his private life and in his dealings with people practised the high virtues of morality and resignation; just as he taught them in his maxims with unexcelled brevity and earnestness. The traditions concerning Hillel's life harmonize completely with the sayings which are handed down in his name, and bear in themselves the proof of their genuineness. No wonder that the Babylonian Talmud is richer in traditions concerning Hillel than the Jerusalem Talmud, since the Babylonians were especially careful to preserve the recollection of their great countryman; and in the Babylonian schools of the third century was proudly quoted the saying of the Judean sage Simeon ben Lakish, in which he placed the activity of Hillel on a level with that of Ezra, who also went up from Babylon to Jerusalem.
In mentioning these characteristics, which the Haggadah then already ascribed to Moses' brother, Hillel mentions his own most prominent virtues. Love of man was considered by Hillel as the kernel of the entire Jewish teaching. When a Gentile, who had just been harshly dismissed by Shammai, wished to become a Jew asked him for a summary of the Jewish religion in the most concise terms ("while standing on one foot"), Hillel said: "What is hateful to you, do not do to your fellow: this is the whole Law; the rest is the explanation; go and learn" (Shab. 31a). With these words Hillel recognized as the fundamental principle of the Jewish moral law the Biblical precept of brotherly love (Lev. xix. 18).
From the doctrine of man's likeness to God, Hillel deduced man's duty to care for his own body. According to Midrash Leviticus rabbah he said "As in a theater and circus the statues of the king must be kept clean by him to whom they have been entrusted, so the bathing of the body is a duty of man, who was created in the image of the almighty King of the world." In this work Hillel calls his soul a guest upon earth, toward which he must fulfill the duties of charity.
In Avot, Hillel stated "If I am not for myself, who will be? If I am not for others, what am 'I'? And if not now, when?" The third part contains the admonition to postpone no duty, the same admonition which he gave with reference to study (Avot 2:4): "Say not, 'When I have free time I shall study'; for you may perhaps never have any free time."
The precept that one should not separate oneself from the community, Hillel paraphrases, with reference to Eccl. iii. 4, in the following saying (Tosef., Ber. ii.): "Appear neither naked nor clothed, neither sitting nor standing, neither laughing nor weeping." Man should not appear different from others in his outward deportment; he should always regard himself as a part of the whole, thereby showing that love of man which Hillel taught. The feeling of love for one's neighbor shows itself also in his exhortation (Avot ii. 4).
In the following maxim is expressed also his consciousness of his own insufficiency: "Trust not thyself till the day of thy death." How far his love of man went may be seen from an example which shows that benevolence must act with regard to the needs of him who is to be helped. Thus a man of good family who had become poor Hillel provided with a riding horse, in order that he might not be deprived of his customary physical exercise, and with a slave, in order that he might be served (Tosef., Peah, iv. 10; Ket. 67b).
This narrative has the same points as the epigrammatic group of Hillel's sayings (Avot. 2:7) commencing: "The more flesh, the more worms," and closing with the words: "Whoever has acquired the words of the Law has acquired the life of the world to come." In an Aramaic saying Hillel sounds a warning against neglect of study or its abuse for selfish purposes: "Whoever would make a name (i.e. glory) loses the name; he who increases not [his knowledge] decreases; whoever learns not [in Ab. R. N. xii.: "who does not serve the wise and learn"] is worthy of death; whoever makes use of the crown perishes" (Avot. 1:13).
This is based on a part of the Passover Seder (the annual commemoration of the Exodus from Egypt), in the section of Korech, where the Haggadah, the ancient liturgy, instructs participants to take the matzo and wrap it around the bitter herbs and eat them together whilst saying in Hebrew: This is a remembrance of Hillel in Temple times — This is what Hillel did when the Temple existed: he used to enwrap the Paschal lamb, the matzo and the bitter herbs and eat them as one. In the Ashkenazi tradition, the usual practice is to do this by making a matzo and horseradish sandwich.
However, it is more likely that matzo in Hillel's day was not hard and crisp but soft. Thus, Hillel would have been eating something more like a lamb, lettuce and lavash (or tortilla-like) "wrap", similar to a burrito, than a traditional English closed sandwich.
Additionally, the Hittite Empire has records of troop provisions in the form of meat stuck between two slices of bread more than a millennium before Hillel.