Praise of disregard
Imagine, for example, that you receive an angry email from someone and there is nothing you can do about the person's grievances. You read it. You accept your inability to change the situation. Then you delete it. Instead of leaving it in your inbox to pull your thoughts toward an irrevocable past, the symbolic act of throwing it away frees your mental energies for more worthwhile pursuits. This is a metaphor, of course. It is probably quite easy for you to delete an email that bothers your brain. But thoughts, which are as virtual as email, can be gotten rid of as well. In all their immateriality, thoughts and emails still impose an extraordinary amount of authority and influence on our actions and frames of mind. Doing away with them has the same effect as removing a concrete obstacle from sidewalk ahead of you.