brentano was at work on "psychology from an empirical standpoint" in 1873, while travelling in europe after leaving the roman catholic church and resigning from his position at the university of würzburg. he completed the first two books of the work in march 1874. brentano originally intended to produce a large work consisting of six books, the first five of which would cover psychology as a science, mental phenomena in general, and their three basic classes, while the sixth would deal with the mind-body problem, the soul, and immortality. however, brentano was ill with smallpox after publishing the first two books. the work remained incomplete. in 1911, brentano published book two of "psychology from an empirical standpoint" under the new title "von der klassifikation der psychischen phänomene", with the addition of remarks explaining his later views, where they differed from those he held in 1874.