What you expect and what you need

What does exactly "what you expect and what you need" imply in the following context? Does it mean "both what you expect to see and what you do not expect to see but is necessary for you to see"?

Context:

What is war art? Is it a battlefield scene with churned-up blood-red earth, driving rain, smoking ruins, scattered corpses, and twisted metal detritus, all lit by white diagonal stripes of searchlights and the brilliant firework colours of exploding star shells? Is it courage in the tired, drawn features of Victoria Cross winners and tragedy in the weary, frightened faces of the ordinary men and women who lived only long enough to be portrayed? Is it teamwork in the charges of galloping horses, the billowing sails of ships-of-the line, the humming squadrons of bomber aircraft, and the concentration of myriad factory workers? Is it the elegant monuments to victory and the spare, minimalist memorials to tragedy? Is it brutal in-your-face gratuitous violence? Is it a gentle, meditative wash of colour depicting no man’s land? This book has tried to explain that it is both what you expect and what you need. It is humankind portrayed at its best and at its worst. It is the record of civilization when life takes second place to death. It is the place where we reflect and remember.