Although the concept of Multiple Intelligences had existed for some time, Gardner brings fresh thoughts to the subject. His book "Frames of Mind" explains a non exhaustive list of human intelligences.
The book is an academic study primarily written for experts in his field. Although good, it can be tough to read for people outside the field. Thomas Armstrong helped interpret these intelligences for the general population in his book: 7 Kinds of Smart.
Having said that, Frames of Mind it is a powerful work that is worth investing the time to read and understand for those who want to understand the roots of the subject.
Whether there are seven kinds of intelligences or more is not that crucial, nor is the possibility that there are subsets to any or all of these different types of intelligences.
What is important is that if there are multiple intelligences, (and I for one agree), then a whole new world of opportunities awaits those who are willing to learn their true strengths and passions in life.
Formal schooling puts strong emphasis on Logical-Mathematical and Linguistic intelligence. Musical Intelligence (music class), Body Kinesthetic and Spatial-Intelligence (gym), Interpersonal Intelligence (intertwined in all classes--getting along with others), and Intrapersonal Intelligence (not taught much) are considered lower priority intelligences in our schools. Logical-Mathematical and Linguistic intelligences are clearly important. However, knowing about and exploring your other intelligences is beneficial as well.
Knowing that you possess other intelligences and the ability to pursue your natural gifts (full or part time) can be a liberating experience and a spiritual awakening!The Re-Discovery of Common Sense: A Guide To: The Lost Art of Critical Thinking