Everything
The argument for valuing the unknown more than the known is this: if you have the knowledge, beliefs, would stand up for any thing, then you imply the access of an objective order by your mind, the subjective. Now, of this objective order, we often feel we are making progress in understanding; and when it comes to the question of whether or not we could ever be right, that an individual could understand everything, you will always object and say, “but how could you possibly understand the past, where all is lost;” you might say “reality is too vast and complex to be understood by any single person,” or “how could I, terrible, and stupid and bad at everything as I am, be progressing in such a positive direction?”—and to be honest, it is only your venture to discover all the bad sense in these objections. Why would a terrible stupid person be good at understanding everything? Well, maybe the popular conception of “everything” includes a lot of trick puzzles that aren’t worth the time to solve again; and your “stupidity” is actually an intelligent refusal to participate again, to selfishly and vainly watch yourself complete with ever grander images of your not-necessarily-so-recent latest real achievement or failure. Maybe. But, and this is key, there is nothing inherently wrong with this concept, but “only… comparing it with images of past experiences makes it so. For example, and it does pain me to write this, maybe you are fond of solving every problem in a given textbook, or of doing your hair every day. There is nothing wrong with these, and indeed who would ever argue that knowledge of everything cannot be communicated with the sense of old and “new” textbooks or the language of scissor fingers, however even today it is all-too-common for, as Nietzsche says, people to play the games where they have the loaded dice—: altogether, then, it is only bad think or “lack of” thinking that can cause an objection, belief, claim, “idea”, etc. to exist, even be worth having in view, not “be totally covered”, —and so with regards to the question, it resolves to being a matter of conscience, of courage and heart, sacrifice, in deciding whether you want to live your life as if we can truly understand everything, or not. After all, history’s burned melting pot of ideas and views, evil and good and right and wrong and left, can be salvaged as the optimally bleak, hard, lifeless carbon dust from which the grandest flower grows outs—or does that feel wrong?