A dependent clause is like a ...

A dependent clause is like a dependent child: incapable of standing on its own but able to cause a lot of trouble.
 William Safire

Quotes from the same author

A reader should be able to identify a column without its byline or funny little picture on top purely by look or feel, or its turgidity ratio.
 William Safire
A reader ought to be able to hold it and become familiar with its organized contents and make it a mind's manageable companion.
 William Safire
In lieu of those checks and balances central to our legal system, non-citizens face an executive that is now investigator, prosecutor, judge, jury and jailer or executioner. In an Orwellian twist, Bush's order calls this Soviet-style abomination 'a full and fair trial.'
 William Safire
You don't overturn a previous court's decisions lightly and I think most Americans are somewhere in the middle on abortion and there's not going to be a revolution here at all.
 William Safire
The Latin motto over Poindexter's new Pentagon office reads Scientia Est Potentia - "knowledge is power." Exactly: the government's infinite knowledge about you is its power over you.
 William Safire