Handbook of Conducting
The conductor is more than the chief musician or a human metronome; the conductor shapes the music and its interpretation. This is the classic handbook for conductors in training, and it's a useful tool for anyone who wants to understand just what's going on up there on the podium (besides baton-waving and displays of rank egotism) and why, whether you're a serious musician or an armchair conductor. The book runs through the basics--"On Conducting" and "The Science of the Orchestra"--and into the more esoteric aspects of music-making as well.