Many of the papers in my collected works were originally written under one set of disadvantages, and are now revised under another. They were written generally under great pressure as to time, in order to catch the critical periods of monthly journals; written oftentimes at a distance from the press (so as to have no opportunity for correction); and always written at a distance from libraries, so that very many statements, references, and citations, were made on the authority of my unassisted memory. Under such circumstances were most of the papers composed; and they are now reissued in a corrected form, sometimes even partially recast, under the distraction of a nervous misery which embarrasses my efforts in a mode and in a degree inexpressible by words. Such, indeed, is the distress produced by this malady, that, if the present act of republication had in any respect worn the character of an experiment, I should have shrunk from it in despondency. But the experiment, so far as there was any, had been already tried for me vicariously amongst the Americans; a people so nearly repeating our own in style of intellect, and in the composition of their reading class, that a success amongst them counts for a success amongst ourselves. For some few of the separate papers in these volumes I make pretensions of a higher cast. These pretensions I will explain hereafter. All the rest I resign to the reader's unbiased judgment, adding here, with respect to four of them, a few prefatory words--not of propitiation or deprecation, but simply in explanation as to points that would otherwise be open to misconstruction.