As can be seen in individual personalities, it seems very appropriate to make a distinction in literature between authors whose spirit is inclined toward knowledge and authors whose spirit is inclined toward pleasure. Poetry, more than other genres, shows that these are very different types, in which the years bring about different transformations, so that, for the former, the work seems to be much more dependent on this evolution. Thus, the tendency is for the former to produce their best work at the end, with their early books taking on a somewhat preparatory character, of greater interest to the biographer than to the ordinary reader. For the latter, it is not uncommon for maturity to spoil that youthful verve on which their best compositions depend.