What is our real problem? Is it external uncleanness? Can we wash ourselves? How can we be made right before God? Jesus reveals the nature of our hearts (minds): it is our heart which is the source of defilement before God. This is an unpopular truth in modern Western culture, where innocence is presumed. But Jesus never assumes the basic goodness of humanity. The context of this passage shows us that Jesus has come to rescue us from ourselves. By faith in Christ we can be washed clean and made right before God.
https://stjohnsrichmond.ca/wp-content/uploads/2016/03/SE2008Jul06.mp3