Hieroglyphics of Horapollo, tr. Alexander Turner Cory, [1840], at sacred-texts.com

p. 116

XLVIII. HOW A MAN THAT HAS NO BILE, BUT RECEIVES IT FROM ANOTHER.

When they would symbolise a man who has naturally no bile but receives it from another, they depict a DOVE WITH HER HINDER PARTS ERECT; for in them she has her bile.