I wrote recently on the blog about my re-reading of Herbert Butterfield's Whig History, a collection of essays every bit as good the second time around as the first. That re-reading prompted me to pull out another classic of historiography: R. G. Collingwood's Idea of History.
No doubt, Collingwood's essays are more challenging than Butterfield's: they're properly philosophy, some of them, and require expert training. But others, including Collingwood's exploration of the contrast between history and science, for instance, are accessible to a popular audience, and are worth the read. If nothing else, Collingwood's work celebrates the power of the human mind - and the human capacity for critical thought.
I'll leave the last word for him:
"It is the truthfulness and the information of the so-called authority that are in question; and this question the historian has to answer for himself, on his own authority. Even if he accepts what his authorities tell him, therefore, he accepts it not on their authority but on his own; not because they say it, but because it satisfies his criterion of historical truth."