* Because the debugging information provided by the interpreter is often less useful than the information

on possible errors you have in your head when writing code.

* Because errors causing execution to stop are frustrating if you're in the middle of a large computation.

* Because it's reduces confidence in your code on the part of your users (if you are writing for others).

* Because it reduces confidence in your code on the part of your users (if you are writing for others).

### Assertions