Painting ceiling : with or without primer?

The builder of our newly constructed house did not paint the ceilings.
He left a dry wall with a pattern on it. We want to paint. Should we
put a primer first or is paint for the ceiling good enough? The
painter says paint is good enough - but he may be interested in given
a low bid.

A good answer explains why we should or should not use a primer for
painting the ceiling, ideally with a reference on the web or a book.

Thank you 

Matt

If you don't use a primer, you can use 2 coats of paint which will be
cheaper than buying primer and paint.

Straight drywall should always have primer first.  The primer will
stick better to the drywall.  It will also cover up the imperfections.
 Two coats of paint will be cheaper (by about $10), but the primer
will look much better and you will definitely only need one coat of
primer and one coat of paint.

being a Professional Painter...

you need to use a Primer almost always when you paint.
Any Painter that is seems "cheap", is cheap, and will dilute paint and
cut corners.  The paint job may look nice when completed, but over
time, you will notice fading, peeling, marks, bleeding, chipping and a
host of other problems.

If painting with latex/acrylic based paint, 1 coat of primer with
backroll, plus 2 coats of flat latex paint will be perfect.  If you
are a heavy smoker, i would tend to use 1 coat of OIL primer and 2
coats of FLAT oil/alkyd paint.

Primer is used as it does many things and benefits the finish and last
of the paint job.  It actually seals the wall, and creates a bond
between the drywall and the paint.  Primer is in no way just white
paint.  The chemical MDS data sheets clearly show this.

Ok, for the bathroom, make sure you use bathroom paint.  It protects
againts moisture seeping through into the walls, and helps reduce
mildew growth.

Also, make sure you pole-sand between coats to get a better finish and bond.

Personally recommend Sherwin-Williams and Para.  Stay away from
designer paints, its the name you are buying, and the quality is
usually on or below par with regular hardware store paint.

Good Luck...

Following up on the recommendation for smoking households, oil-based
semi-gloss enamal is another possibility; it wipes clean far better
than flat paint. Semi-gloss (oil or water-based) also gives a certain
glossiness to the surface; your room will be brighter (this is a trick
favored in Europe, but interesting has not be picked up on here in the
US).

Ditto the comments on applying primer to drywall. ALWAYS primer raw
drywall. Regular paint will allow the imperfections of the paper to
telegraph right through. Even a second coat of plain latex will not
make it look good. Spend a few more dollars and apply a good primer (
I use 1-2-3 Primer available at Home Depot or Lowes) and put it on
THICK!! Then hit it with your desired color once it's good and dry (
couple days).

   http://www.zinsser.com/product_detail.asp?ProductID=11

Piko