Augustine of Hippo : Just as Jacob, again, was not the creator of the colors in the flocks, because he placed the various colored rods for the several mothers, as they drank, to look at in conceiving. Yet neither were the cattle themselves creators of the variety of their own offspring, because the variegated image, impressed through their eyes by the sight of the varied rods, clave to their soul, but could affect the body that was animated by the spirit thus affected only through sympathy with this commingling, so far as to stain with color the tender beginnings of their offspring. For that they are so affected from themselves, whether the soul from the body, or the body from the soul, arises in truth from suitable reasons, which immutably exist in that highest wisdom of God Himself, which no extent of place contains; and which, while it is itself unchangeable, yet quits not one even of those things which are changeable, because there is not one of them that is not created by itself. For it was the unchangeable and invisible reason of the wisdom of God, by which all things are created, which caused not rods, but cattle, to be born from cattle; but that the color of the cattle conceived should be in any degree influenced by the variety of the rods, came to pass through the soul of the pregnant cattle being affected through their eyes from without, and so according to its own measure drawing inwardly within itself the rule of formation, which it received from the innermost power of its own Creator. — On the Trinity 3.2.15 Jerome : (Ver. 41 and 42.) And the flocks conceived against the rods that Jacob had set before the flocks in the gutters, so that they conceived by the rods; but the sheep that were weak, he did not put the rods. And Laban's flocks were weak, but Jacob's were strong and healthy. This is not found in the Septuagint Interpreters, but instead of the weak and healthy ones, they translated something else, I don't know what, which does not make sense. But what the Scripture says is this: Jacob, wise and clever, observed justice and fairness even in a new way. For if all the ewes and goats were producing various offspring, there would be some suspicion of deceit, and openly Laban, envying this situation, would oppose it. Therefore, he managed everything in such a way that he himself would benefit from the result of his labor, and Laban would not be completely deprived. If ever the sheep and goats were bred in the early season, because the spring offspring is better, he would place rods in front of them so that diverse offspring would be born. But whatever sheep and goats were bred late and were seeking a male, he would not place objects in front of their eyes so that animals of a single color would be born. And whatever was first born belonged to him, because it was different and varied: whatever came after, belonged to Laban: for from one colored cattle, both black and white, were born. But in the place where it is written, that they conceive in rods: in Hebrew it has Jeamena (). I cannot express the force of the Hebrew word without going around it. Jeamena properly means the extreme heat in sexual intercourse, by which the whole body trembles, and is near the end of pleasurable satisfaction. — Hebrew Questions on Genesis