And Jacob did separate the lambs, and set the faces of the flocks toward the striped, and all the brown in the flock of Laban; and he put his own flocks by themselves, and put them not with Laban's flock.
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Cyril of Alexandria
There is no association between the holy and the profane, between the pure and the impure. Those who belong to Christ are separated and refuse to mix with those who are in the world; they are free from carnal desires. They are marked by their way of life or rather are distinguished by their virtue. “The unmarked ones were Laban’s, and the marked ones were Jacob’s.” ,
All the white Notwithstanding Jacob's stratagem, some had lambs all of a colour. The force of fancy is very surprising on such occasions. Oppian, Aristotle, and others, recommend Jacob's plan as consonant to nature. (Haydock)