The midwife does something quick and symbolic. As Tamar's twins are being born, one child stretches out a hand from the womb, and the midwife binds it with a scarlet thread, saying, This came the first (Genesis 38:28). The Targum Pseudo-Jonathan preserves the gesture in its austerity; it does not yet comment. The interpretation is waiting in the next verse, when the hand withdraws and a different brother breaks through.
The Sages read the scarlet thread as a small lesson about the stories we tell while the outcome is still in the womb. The midwife is doing her job — she is marking what appears first, so that inheritance can later be traced. She is being careful and reasonable. And she is going to be wrong, because the child whose hand came first is not the child who will be born first.
Bereshit Rabbah 85 draws a long thread (literally) from this scarlet cord all the way to the scarlet cord Rahab will later hang from her window at Jericho (Joshua 2:18). The color tzur, crimson, becomes in the tradition the sign of a promise kept across generations — a visible mark binding one story to another. The targumic retelling, redacted in the Land of Israel in the early common era, knows the thread is not a mistake. It is simply a record of what was visible at the time.
The takeaway is about how inheritance actually works. The first hand is not always the first-born; the sign we tie on the world is honest, and still often provisional. What looks like the decided order at the moment of appearance can be reversed by a single breath. The scarlet thread is a quiet reminder to hold our predictions loosely — the one reaching first is not always the one who will arrive.