Individuals and interactions over process and tools
In your face and deal with it! People, relationships, behavior, psychology, group dynamics, feelings, emotions, attitudes, personalities, communication, introverts, extroverts, judgments, power, powerless, control, trust, it just goes on and on.
It is much easier for an engineer to hide behind a defect tracking tool, source code management tool or requirements management tool than actually talking with the quality engineer, development partner or customer. We (engineers, project managers, managers) have had years of training and experiences in working with computers, communicating with documents, email, instant messaging, blogging, online shopping, and online dating.
How are we (am I) suppose to come out from behind our (my) computers (phones, PDA’s, IPods)? How are we (am I) supposed to share a room with them (coworkers) and be more productive? Ha! Good luck. We (I) got into this business because we (I) like to work with computers.
You get the point
The other statements in the Agile Manifesto are “customer collaboration over contract negotiation”, “working software over comprehensive documentation” and “responding to change over following a plan”. Without ranting any further (and playing the coach that I am), I will let you extrapolate the human side of each of these.
Software development is hard because it requires mastering the soft side (right brain, creative, complex, out-of-the-box, illogical, irrational) of humans. Agile is just a set of principles that recognize this and provide you a roadmap to help you gain value from them (humans).
Technology has brought us closer to others in the world (the world is flatter) and yet more distant to those around us. The 90’s taught us that we could correct people with process. We know now that doesn’t work. If we master the human side of application development, we can maximize our business value.