Lectures on the weekly Torah reading by the faculty of Bar-Ilan University in Ramat Gan , Israel . A project of the Faculty of Jewish Studies, Paul and Helene Shulman Basic Jewish Studies Center, and the Office of the Campus Rabbi. Published on the Internet under the sponsorship of Bar-Ilan University 's International Center for Jewish Identity. Prepared for Internet Publication by the Computer Center Staff at Bar-Ilan University . Inquiries and comments to: Dr. Isaac Gottlieb, Department of Bible, email@example.com
Numerology is an area of study where the number-words in a Hebrew text have symbolic significance. We are not speaking of gematria, or the numerical value of Hebrew words, but rather of actual numbers in the biblical text. In the eyes of a numerologist, these values are not incidental, but deliberate, and he tries to explicate them, an area which is generally ignored by the traditional commentators. For him, analysis of the numbers can serve as an additional literary tool to help us understand the message of the text. Below we seek to explain one case of numerology that appears in Parashat Ve-Yehi. 
This week’s reading begins with the following statement: “Jacob lived seventeen years in the land of Egypt, so that the span of Jacob’s life came to one hundred and forty-seven years” (Gen. 47:28). The first part of this verse calls for explanation. It is surprising that Scripture tells us Jacob lived in Egypt for seventeen years, since the reader could have reached that conclusion by himself, for in the same chapter we are told that Jacob presented himself before the Pharoah and told him he was one hundred and thirty years old (Gen. 47:9). Since Jacob lived a total of one hundred and forty-seven years, a simple exercise in arithmetic leads us to the conclusion that he lived seventeen years in Egypt. That being so, what does Scripture seek to teach us?
The Sages, who were sensitive to all shades of meaning in the scriptural text, also set their minds to this question, and several medieval commentators followed their lead.  They observed that the number seventeen that appears here also appears when Joseph left his father (Gen. 37:2), and understood that it was not for naught that Scripture specified both Joseph’s age and the number of years Jacob lived in Egypt. This is to say that both statements about seventeen years are references one to the other, their intention being to establish a relationship of measure for measure, middah keneged middah.  Just as Jacob supported his son during his first seventeen years, so the son supported his father during his last seventeen years.
Put differently, the number which seems to be superfluous comes to teach us proper behavior towards our parents; a person must care for his mother and father in their old age, just as they cared for him when he was a child. Rather than being instructed explicitly to respect and honor our parents, in the way of the biblical story we get an oblique assertion of this idea through the contrast of measure for measure.
This idea has not received the attention it deserves; however we do find that Rashi gave prominence to a similar idea. The Sages, says Rashi, noted that just as Jacob had been absent from this father’s home for twenty-two years (a number derived from the verses, but far from being unequivocal), so Joseph was absent from his parents’ home for twenty-two years (also a number not explicitly stated in Scripture). In other words, we have another case of numerical “measure for measure”. For the number of years that Jacob did not honor his father, so too Joseph did not honor his father – one might say a sin and its retribution, and this lesson is taught in the same walk of life that we observed above-- honoring one’s parents. An oblique statement is being made here, just as in the previous passage: whoever does not respect and honor his parents should know that a similar fate awaits him, insofar as the acts of the parents forebode the acts of the children.  As the father did not honor his father, so too the son.
Closely examining Genesis, we discover that this idea of measure for measure in the area of honoring parents appears a third time, also via numerology. It is said that Abraham was seventy-five when he left Haran (Gen. 12:4), which means that he honored his father as long as they were living together (even if this is not explicitly stated). Now Isaac was born when his father Abraham was one hundred years old (Gen. 21:5), and presumably honored his father until Abraham’s death at the age of one hundred and seventy-five (Gen. 28:7). In other words, Isaac honored his father Abraham for seventy-five years, just as Abraham honored his father Terah (an idol worshipper, as opposed to his son) for seventy-five years. Here is a third example from Genesis of the principle of measure for measure in the matter of honoring parents, this time also hinting that a convert must honor his non-Jewish parents. 
The general rule is that when a number appears in the text and that number seems to be superfluous and to no point, it turns out to be conveying a meta-textual message (an idea that appears obliquely in the text). Three times numbers convey hints to us about the reciprocity in relations between fathers and sons. Scripture hints to the reader about the duty to honor one’s parents, but it does not say this explicitly in the form of a commandment; rather, the text relies on the idea of measure for measure, a fundamental principle for understanding retribution and reward in the biblical text. It is amazing how new interpretations can be discovered for familiar Torah portions (in contrast to the Prophets or Writings), and how numbers as a source of meaning have been largely overlooked by Bible commentators.
 This article is an abridgement selected from M. Bar-Ilan, Numerologiya Bereshitit, second edition, Rehovot 2004.
 S. Buber (compiler), Midrash Aggadah al Hamishah Humshei Torah: Genesis-Exodus, Vienna 1894, p. 105; M. M. Kasher, Torah Shelemah, 7, New York 1950, p. 1724.
 Yael Shemesh, “Middah ke-Neged Middah ba-Siporet ha-Mikra’it,” Beit Mikra, 49/158 (1999), pp. 261-277. There are other instances of measure for measure in Genesis, such as 1) Jacob as the deceiver deceived; 2) Joseph’s brothers as enslaving and enslaved; 3) the years of plenty as against the years of famine.
 This idea was developed by Nahmanides in his commentary on Genesis 26:29: “As the fathers did, so did the sons,” and can be illustrated by other instances. Cf. Ezra Melamed, Mefarshei ha-Mikra: Darkheihem ve-Shitotehem, II, Jerusalem 1975, pp. 950-952.
 In the Shulhan Arukh, Yoreh De’ah 240.18 it says: “Even if his father were wicked and sinful, nevertheless he should respect and fear him.” The gloss reads: “Some say that one is not obligated to respect a wicked father, unless he has repented.”