Let’s dive into a passage from Bereshit Rabbah, a collection of rabbinic interpretations of the Book of Genesis, and unpack some of the ideas around yibum, or levirate marriage.

The story begins with Judah and his sons. You might remember the verse from Genesis 38:8: "Judah said to Onan: Consort with your brother’s wife, and consummate levirate marriage with her, and establish offspring for your brother." According to Bereshit Rabbah, this makes Judah the first to initiate the mitzvah, the commandment, of levirate marriage.

But what exactly is levirate marriage? Simply put, it's what happens when a man dies without children. His brother is then obligated to marry the widow, known as the yevama, and any son born from that union is considered the heir of the deceased brother, thus continuing his line. The yevama is in a unique state, bound to her deceased husband's brother, who is called the yavam.

The text brings up an interesting legal concept: "Any matter that was in the category of permitted, became prohibited, and then became permitted again, it does not return to its initial permitted state, but rather, to a second permitted state." Confusing, right? Let’s break it down.

Think of the yevama. Before she married her deceased husband, she was permitted to marry his brother. Once she married, she became forbidden to him. Now that her husband has died, she's again permitted to marry him, but only under the specific conditions of yibum.

So, does she return to her initial state of permissibility? No. Deuteronomy 25:5 states: “Her husband’s brother shall consort with her” – mitzvah. This highlights that the act must be performed as a commandment, with the proper intention, and not simply because the two individuals desire to be married. The Yefe To’ar commentary clarifies that before her first marriage, they could have married for any reason; now it must be for the sake of fulfilling the mitzvah.

The text then shares a fascinating story about Rabbi Yosei bar Ḥalafta, who actually entered into levirate marriage with his brother’s wife—multiple times, actually! He apparently had five brothers who died without children, and he engaged in relations five times, each time through a sheet, to minimize his pleasure and ensure his intention was purely for the sake of the mitzvah.

And the result? He "planted five saplings in Israel," meaning five sons were born from these unions: Rabbi Yishmael ben Rabbi Yosei, Rabbi Elazar ben Rabbi Yosei, Rabbi Menaḥem ben Rabbi Yosei, Rabbi Ḥalafta ben Rabbi Yosei, and Rabbi Avdimos ben Rabbi Yosei. The text even notes that Rabbi Avdimos had red eyes and resembled his mother, a detail that underscores Rabbi Yosei's focus on fulfilling the mitzvah, even when the woman wasn't considered attractive.

Then we get back to Onan. Genesis 38:9 tells us, "Onan knew that the offspring would not be his, and it was when he consorted with his brother’s wife, that he spilled on the ground, so as not to give offspring for his brother.” The Rabbis interpret “Onan knew” to mean he would penetrate but spill outside, a deliberate act to avoid fulfilling the obligation. This is where we get the term "onanism," though the passage is really about the intent behind the act, not the act itself.

Finally, the passage touches on Judah's statement to Tamar, his daughter-in-law: "Remain a widow in your father’s house, until Shela my son matures; for he said: Lest he too die, like his brothers." Rabbi Elazar sees this as a portent. Even though divination is generally prohibited, there's a sense that certain events can foreshadow future outcomes. The Rabbis extend this idea, noting that with a house, a baby, or a wife, an experience can be seen as a sign for future fortune.

So, what can we take away from all of this? The passage reveals the complex and nuanced thinking that went into developing Jewish law, particularly around issues of family, lineage, and obligation. It reminds us that even seemingly straightforward commandments can be filled with layers of meaning and interpretation. And it makes you wonder, doesn't it, about all the unseen forces shaping our own lives and choices?