While most management practices are based on proven ideas, the individuals being managed are far too unique and variable for management to be anything other than an art. There are simply too many effective management styles for there to be any solid and codified principles that govern them all.
Whether guiding a small team of employees or directing an entire company, management is the art of understanding how all of the disparate parts of an organization work together to achieve a unified goal. This may be small-scale management, overseeing just a few individuals, or it may be large scale, requiring the orchestration and coordination of many different departments, each with its own managers. However, at any level, managing is about learning what drives and motivates those being led and using it to leverage productivity and efficiency as the group or company at large drives toward a common goal. These motivating factors are so different, and the means of applying them so varied, that trying to boil it all down to a few immutable laws is difficult at best. Many professional development gurus have written, and even lectured, on the most effective way to manage a group, but few of them agree on anything more than the broad brushstrokes.