My reference was not Perl-specific.

Yeah, it took me a while to wrap my head around Perl's compilation / runtime phases, too. One thing in particular that seems to throw people off sometimes is that use is essentially like an eval inside of a BEGIN. I recommend this reading because that's what helped me understand: BEGIN, UNITCHECK, CHECK, INIT and END in perlmod, and in this order: use, require, do, and eval.