The Da Vinci Notebooks at sacred-texts.com
We read of the kite that, when it sees its young ones growing too big in the nest, out of envy it pecks their sides, and keeps them without food.
Cheerfulness is proper to the cock, which rejoices over every little thing, and crows with varied and lively movements.
Sadness resembles the raven, which, when it sees its young ones born white, departs in great grief, and abandons them with doleful lamentations, and does not feed them until it sees in them some few black feathers.