Nietzsche opens with the suggestion that our knowledge relies on a simplification of the truth that makes it expressible in language and understandable to all. Essentially, then, our will to knowledge is built upon, and is even a refinement of, our will to ignorance. Philosophers most of all should not pose as defenders of truth or knowledge. The "truths" of philosophers are just their prejudices, and no philosopher has even been "proved" right. Philosophers are at their best when they are questioning themselves and freeing their spirits from their prejudices.
The "free spirits" among us thrive on isolation and independence, though this is a difficult and dangerous life to follow. On one's own, one faces unknown dangers that no one else will understand. One's successes and failures are entirely one's own and cannot be shared. The thoughts of these free spirits are liable to be misinterpreted and dangerously misunderstood by lesser people. Still, free spirits devoted to knowledge will commit themselves to forgoing their independence and mingling with others. In terms of knowledge, the rule is more interesting than the exception.
Nietzsche draws a brief contrast between "pre-moral" societies where the value of an action is found in its consequences, and modern, "moral" societies where the value of an action is found in its origin. Today, we praise or blame an action primarily based on its motives. Nietzsche identifies in this an advance over the "pre-moral" valuation since this "moral" worldview places an emphasis on self- knowledge. However, he also looks beyond our "moral" world to an "extra- moral" world that recognizes that the true value of an action lies beneath the conscious level in the unintentional drives that motivate it. We need to "overcome" morality, recognizing that the intentions and motives for actions are just the surface of a far more complex set of drives that need to be uncovered and analyzed.
After a skeptical onslaught in which Nietzsche questions the value of thought, truth, morality, and pretty much everything else that has served as a basis for philosophy, he suggests that we admit nothing as "real" except our drives, desires, and passions. Thought, for instance, he suggests, is ultimately just the relation of our different drives to one another. Can we, he asks, also explain the workings of the mechanistic, material world using just our drives as data? If just one agent of causation--will--explains all change, we needn't look for additional causes.
We might interpret the material world not as separate from the organic world, but as a primitive form of the organic world, from which organic life springs. Will does not affect nerves or dead matter, but only other wills. However, if we can trace all our drives back to a fundamental will to power, as Nietzsche proposes, we can then interpret the world and its "intelligible character" based entirely on the will to power.
Nietzsche concludes by returning to the nature of free spirits and profound thinkers. These people often need "masks" to disguise their true nature. Most people are unable to understand them, and so will necessarily understand them differently from what they truly are. In order to be independent, they must constantly test themselves and not allow themselves to become attached to anything, be it other people, their fatherland, science, or even the spirit of detachment itself or the virtues they admire in themselves. Nietzsche identifies the new species of philosophers that he sees coming as "attempters," free spirits who will shun dogmatism and embrace the hardships of independence of mind and spirit.