You may be interested in Human, All Too Human: A Book for Free Spirits by Friedrich Nietzsche, recently released over at Project Gutenberg.
“All philosophers make the common mistake of taking contemporary man as their starting point and of trying, through an analysis of him, to reach a conclusion. ‘Man’ involuntarily presents himself to them as an aeterna veritas as a passive element in every hurly-burly, as a fixed standard of things. Yet everything uttered by the philosopher on the subject of man is, in the last resort, nothing more than a piece of testimony concerning man during a very limited period of time. Lack of the historical sense is the traditional defect in all philosophers. Many innocently take man in his most childish state as fashioned through the influence of certain religious and even of certain political developments, as the permanent form under which man must be viewed. They will not learn that man has evolved, that the intellectual faculty itself is an evolution, whereas some philosophers make the whole cosmos out of this intellectual faculty. But everything essential in human evolution took place aeons ago, long before the four thousand years or so of which we know anything: during these man may not have changed very much. However, the philosopher ascribes ‘instinct’ to contemporary man and assumes that this is one of the unalterable facts regarding man himself, and hence affords a clue to the understanding of the universe in general. The whole teleology is so planned that man during the last four thousand years shall be spoken of as a being existing from all eternity, and with reference to whom everything in the cosmos from its very inception is naturally ordered. Yet everything evolved: there are no eternal facts as there are no absolute truths. Accordingly, historical philosophising is henceforth indispensable, and with it honesty of judgment.”