A battle rages in all of us for the control of our minds. Satan has controlled our thought process up to the point of salvation. The Holy Spirit takes over making our justification obvious through our sanctification.
In school we learned about bullfrogs and butterflies and the process of metamorphosis. That word shows up in this text and it is an illustration of how God changes us.
He finds us.
He frees us.
He fashions us.
He fits us.
He wants to use us but first a metamorphosis takes place. It is constant until we finish our race down here.