Many years ago we learned about the Myers-Briggs personality typing system, and one of the books we read was 'Please Understand Me' by Keirsey and Bates. I found it somewhat useful, but a bit simplistic, and preferred other books. A couple of years ago I discovered that there was a sequel, albeit with a most unimatinative title, by David Keirsey alone. I debated buying it, but decided it was probably just an update.
A bit of a mistake, there. More recently I discovered that it's a complete re-write, with new information and far more helpful descriptions. so I ordered it, and wish I had done so years ago.
Keirsey uses the Myers-Briggs/Jungian terminology in his book, but rather than focusing on 16 different types of people he divides them into four categories, which he calls the Artisan, the Guardian, the Idealist and the Rational. See the Keirsey site for some info about this, but it's not a very attractive site - it's rather badly laid out (in my opinion). However it does contain the Keirsey 'temperament sorter'. Forget any pre-conceived ideas you might have about 'Sensing' and 'Intuiting' - for many years I thought I was an ISTJ Guardian. But online discussion, taking this updated version of the test, and most of all reading the book have almost convinced me I am actually an INFJ Idealist. Hmmm.
For a much more comprehensive site that's pleasant on the eye too, see the 16types site (link leads to the Keirseyan temperament page, but the whole site is well worth exploring).
The book 'Please Understand Me II' contains a great deal more than any of these sites, however, with insights into the ways the different temperaments relate, lead, and even their differing kinds of intelligence. It's not really a book to read straight through, but one to dip into over and over again. However in my determination to understand fully the differences between Guardians and Idealists, and why I might have confused the two, I did read the majority of this book over several days. No doubt it will be a reference book for the whole family in the years to come.
Very highly recommended to anyone interested in learning more about themselves or those around them.