The prenatal influence of visual impressions

[Mudhammam]

Here's a curious passage in Genesis that I hadn't really noticed before today. I came across it while reading Augustine's City of God:

And Jacob took rods of green poplar and of the hazel and chestnut tree, and peeled white strips in them and made the white appear which was in the rods. And he set the rods which he had peeled before the flocks in the gutters, in the watering troughs when the flocks came to drink, that they should conceive when they came to drink. And the flocks conceived before the rods, and brought forth animals ringstreaked, speckled and spotted.

Genesis 30:37-39

Apparently, the biblical writers - and Augustine - believed that if the lambs and goats had a visual impression of stripes while they were mating and conceiving, some kind of prenatal influence would cause the offspring to assume the same form...LOL. Here's Augustine's thoughts on the matter, in the context of the Egyptians worshipping the bull-deity Apis:

When this bull died, a calf of the same colouring was sought, that is, one similarly marked with special white patches; and it was always found. Therefore they supposed it to be some kind of miracle, divinely provided for them. It was, in fact, no great task for demons, bent on deceiving them, to display to a cow which had conceived and was pregnant a phantom of a bull, which the cow alone could see, so that the mother's desire should from that stimulus induce the marks which would then appear in her young. This was how Jacob ensured the birth of parti-coloured lambs and goats by the use of variegated rods. Doubtless what men can achieve, by means of material things and colours, demons have no difficulty in effecting, by displaying unreal shapes to animals at the time of conception.

Book XVIII, chapter 5

I wish I could say that the divine idiocy, which is such a common feature in both of these bloated works, couldn't get much worse (or is better more appropriate here?) but...