Is there any book that you can confidently say is the best book ever written?

for me it's The Art of the Deal

Yes.

>>21976882 (OP)

Thus Spoke Zarathustra.

Nietzsche explains (from Ecce Homo):



This work stands entirely on its own. Let us leave the poets aside: absolutely nothing has ever been achieved, perhaps, from a comparable surfeit of strength. My concept of ‘Dionysian, became the highest deed here; measured against it, all the rest of human action appears poor and limited. The fact that a Goethe, a Shakespeare would not be able to breathe for a moment in this immense passion and height, that Dante, compared with Zarathustra, is just one of the faithful and not one who first creates the truth, a world-governing spirit, a destiny—that the poets of the Veda are priests and not even worthy of unfastening a Zarathustra’s shoe-latches, this is all the very least that can be said and it gives no conception of the distance, the azure blue solitude in which this work lives. 



Zarathustra has an eternal right to say: ‘I draw circles around myself and sacred boundaries; fewer and fewer climb with me upon ever higher mountains—I build a mountain-range from ever more sacred mountains., If you roll into one the spirit and the goodness of all great souls, all of them together would not be capable of producing a single speech of Zarathustra’s. Immense is the ladder on which he climbs up and down; he has seen further, willed further, achieved further than any man. He contradicts with every word, this most affirmative of all spirits; in him all opposites are fused together into a new unity. The highest and the lowest powers of human nature, that which is sweetest, airiest, and most fearsome pours forth from a single spring with immortal assuredness. Till that point people do not know what height and depth are; still less do they know what is truth.



There is not a moment in this revelation of truth that might already have been anticipated or guessed by one of the greatest. There is no wisdom, no soul-study, no art of speaking before Zarathustra; what is nearest, most everyday speaks here of unprecedented things. Aphorisms quivering with passion; eloquence become music; lightning-bolts hurled on ahead towards hitherto unguessed-at futures. The mightiest power of analogy that has yet existed is feeble fooling compared to this return of language to its natural state of figurativeness.—And how Zarathustra descends and says the kindest things to everyone! How he tackles even his adversaries, the priests, with delicate hands and suffers from them with them!—Here man is overcome at every moment; the concept of ‘overman’ has become the highest reality here—everything that has hitherto been called great about man lies at an infinite distance below him. The halcyon tone, the light feet, the omnipresence of malice and high spirits and everything else that is typical of the type Zarathustra has never been dreamed of as essential to greatness.
