The three stages of truth

From the preface to The World as Will and Representation by Arthur Schopenhauer.  

And now that I have allowed myself the jest to which in this two-sided life hardly any page can be too serious to grant a place, I part with the book with deep seriousness, in the sure hope that sooner or later it will reach those to whom alone it can be addressed; and for the rest, patiently resigned that the same fate should, in full measure, befall it, that in all ages has, to some extent, befallen all knowledge, and especially the weightiest knowledge of the truth, to which only a brief triumph is allotted between the two long periods in which it is condemned as paradoxical or disparaged as trivial. The former fate is also wont to befall its author. But life is short, and truth works far and lives long: let us speak the truth.

As so often happens, it is now more pithily, though less true to the original German, rendered as 

All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.