The animals' nature will ensure that whites beget whites and blacks beget blacks, while my righteousness stands with me: God observes my humility and diligence.” Laban willingly accepted Jacob's terms and acted upon them: he distanced Jacob and his family by a journey of three days to prevent any potential deceit due to the closeness of the herds.
Jacob cleverly devised a plan, utilizing his own natural ingenuity to manipulate the characteristics of the white and black cattle. He stripped the bark from branches of poplar, almond, and pomegranate (although the Seventy mention styrax, walnut, and sycamore). This created branches with a mottled appearance; where the bark remained, the original color was intact, and where it was removed, the white was exposed. Jacob waited for the time of mating among the cattle, which would typically gather eagerly at the watering place after the heat of the day. He placed the variegated branches in the troughs. At the peak of their thirst, as he allowed the rams and goats to mate with the ewes, the animals conceived offspring resembling the rams and goats as they saw their reflections in the water. The presence of the branches in the ditches caused the reflections of the animals to appear mottled as well.
It is noteworthy that, during conception, it is common for females to give birth to offspring that reflect what they see or envision in moments of heightened desire. This phenomenon has also been observed among Spanish horse herds. Quintilian, during a legal proceeding in which a reputable married woman was accused of giving birth to a child of Ethiopian descent, presented evidence supporting the very principle I just described. After white and uniformly colored flocks produced motley and two-colored offspring, Jacob separated the latter from the original herd. Any solid-colored offspring, whether white or black, were given to Laban's sons. Jacob continued placing the stripped branches in the water troughs as the animals approached to drink. Thus, the livestock would conceive precisely at the moment they arrived at the watering hole.