What does Catherine's mother mean when she says, "You are so much already, Little bird. why not cease your fearful pounding against the bars of your cage and be content?"
The second born sons were, or course, potential back-up heirs. They were often trained to become soldiers. More rarely, they trained for the church. In some families this was reversed where the second son studied for the church first. Third born sons were almost always steered towards the church, but the option to be soldiers was there. They did not inherit ANY land in the 'middle' Middle Ages - High (late) Middle Ages but were often given some funds, at least enough to outfit them as soldiers.