If Freewill cannot alter fevers how can it subdue the Great Evil?

But I wish to know this : is Freewill the cause of sins, or is Evil the fountain of sins ? But if it is Evil as they say. free Volitions cannot block up the springs of Evil. By what method then is the Evil made subject to our Will ? For, lo, when we wish, we stir it up in us to injure us, and when we will we keep it quiet within so that it cannot harm us. A plain demonstration refutes their obscure Teaching. For, behold, not even a fever within us is subject to our Will, so that when we wish it may rage and abate. If, therefore, this slight fever is not subject to our Freewill, who can make subject to our Freewill that great Evil about which they speak ? If that Evil made itself subject to us, there is nothing kinder than it, for it has made its great power subject to our weak Will. But if the power of Good makes Evil subject to us, it is clear that whenever it hurts us [xxiv] that same Good stirs it up to hurt us. And, therefore, even if that Evil is evil because it hurts us, yet that which permits Evil to destroy us is more evil than it.