Well put! Also, there are the cases when the system does not behave as expected (for example, mis-configuration, or wrong input from the user) - in those cases

Well put! Also, there are the cases when the system does not behave as expected (for example, mis-configuration, or wrong input from the user) - in those cases there are no exceptions or crashes, but a good log will tell you why it happens. I've given a more detailed example of this in example 2 here: http://henrikwarne.com/2013/05/05/great-programmers-write-debuggable-code/ http://henrikwarne.com/2013/05/05/great-programmers-write-de...