Who is Prideful Souls from The Interior Castle and what is their importance?

Prideful souls are another group Teresa warns is those who might be tempted to give themselves credit for the things God reveals to them in worship. She reminds them at nearly every stage of progress that there is nothing a soul does to earn these favors; she cannot even ask for them with pure intentions. Rather it is the grace and prerogative of God to give gifts to whomever He wills, whenever He sees that the time is right. Humility is a virtue to be continually renewed with every new development.