Almost everyone who collects watches is drawn to the mechanics of a watch movement. While the mechanical principals that make a watch 'tic' aren't all that complicated, it's often tough to discern just what's driving what since the parts of a watch movement are so small and the whole works needs to be designed to fit in a space that's necessarily very small.
If you're interested in learning about how all of the parts of a watch movement fit and work together, there isn't a better book to own than Don de Carle's Practical Watch Repairing. Although it's a bit dated, the information and illustrations in this book (along with some judicious practice on some old pocket watch movements) can make anyone comfortable dismantling and reassembling a watch movement. Once you know how to take it apart and put it together, you'll definitely have a much better understanding of the concepts involved and might even attempt a repair or adjustment yourself at some point.
