Every parable has a simple point. We learn how to "hear" the parables. We discuss why Matthew waits until chapter 13 to record parables and Mark introduces them in chapter 4. Pay attention is a work within the regenerated human by God. What you put into it, you get out of it. It does require participation. It is wrong cooperation if we assume retaining the faith is our job. God rewards His own works within us (quote from Augustine). We are called to sow and water, God gives the growth. This is the parable of the Growing Seed.