Martin Fowler's report on OOPSLA contains these gems:
This one I put in the typecasting-is-a-bug-not-a-feature category
Dynamic types are stronger than static types, as they don't flee the field at runtime. --Brian Foote
and this one in the safety-needs-to-be-tested-not-intuited category
Static types give me the same feeling of safety as the announcement that my seat cushion can be used as a floatation device.