copying problem
Placeholder for the idea that there is no 'copy of this object' in Lisp. We should summarise the excellent rants of KMP on this subject.

See also his article Equal Rights --and Wrongs-- in Lisp, that addresses this issue.

See Linear Logic and that hbaker article about CONS not CONSing its arguments... (for example here: here.)

This could be expanded into an online tutorial.