In preparing this edition, only those passages which have been shown by recent researches to be erroneous have been removed. It has not been thought necessary, or even desirable, to modify the wording of Essays (by changes of tense or otherwise) in such a way that, as thus modified, the Essays might have appeared in 1884. In many cases this would have been altogether misleading, whereas, with the dates prefixed to the several Essays, no misconceptions can arise.

Richard A. Proctor.