 The "Philosophy of Arithmetic" constitutes the first volume of a work which Husserl intended to comprise two volumes, of which the second was never published.Comprehensively it would have encompassed four parts and an Appendix.The first volume is divided in two parts, in the first of which Husserl purports to analyse the "Proper concepts of multiplicity, unity and amount" ("Die eigentliche Begriffe von Vielheit, Einheit und Anzahl") and in the second "The symbolic amount-concepts and the logical sources of amount-arithmetic" ("Die symbolischen Anzahlbegrife und die logischen Quellen der Anzahlen-Arithmetik").