Soon after the publication of the _Estetica,_ Croce began to consider his book merely as a programme and a sketch which needed filling in with further developments,--with the investigation of the other forms of human activity, which had been merely postulated in the study of the æsthetic activity; and with a wide cultural work, to be carried on especially by means of a review, through which his ideas should be tested in immediate and constant relation with the problems of contemporary Italian and European thought. The enormous activity of the following years falls easily into this rough division. On one hand we have the completion of the _Filosofia dello Spirito,_ with the _Logica come scienza del concetto puro,_ the first edition of which appeared in 1905 (_Lineamenti di una Logica,_ etc.), and the second, deeply modified by his meditations on the practical activity, in 1909, with the _Filosofia della Pratica: Economica ed Etica,_ written in 1908, but of which some parts had already been given in 1907 in the memoir _Riduzione della filosofia del diritto alla filosofia dell' economia_; and with the new and fuller formulation of his Æsthetics in a paper read to the International Congress of Philosophy in Heidelberg in 1908, on _L'intuizione pura e il carattere lirico dell' arte_. To these must be added the two monographs on Hegel (1906) and Vico (1910), which are at the same time an exposition of their philosophies and a restatement of Croce's own main positions, in so far as they coincided with those elements of truth which he still recognized as living in their thought.