FOUR PERIODS IN HUMAN LIFE.--In the _Convivio_ (iv. 23, 24) Dante represents human life under the image of an arch, ascending and descending. For the perfectly-natured the summit of this arch is in the thirty-fifth year. Life is divided into four ages, like the four seasons of the year. Adolescence, _Adolescenza_, the increase of life, ascends from birth to the twenty-fifth year; Youth or Manhood, _Gioventute_, the perfection and culmination of life, lasts from the twenty-fifth to the forty-fifth year; Age, _Senettute_, descends from the forty-fifth to the seventieth year; after which remains Old Age, _Senio_, the winter of life. THREE PERIODS IN DANTE’S WORK.--Dante’s work falls into three periods, representing to some extent _Adolescenza_, _Gioventute_, _Senettute_. The first is that of his “New Life,” the epoch of the romantic worship of Beatrice in her life and after her death, in which the youthful poet beheld many things by his intellect, as it were dreaming, _quasi come sognado_ (_Conv._ ii. 13). This period comprises the _Vita Nuova_, with the lyrics contemporaneous with it, and closes in the promise “yet to utter concerning her what hath never been said of any woman.” The second period corresponds to Dante’s second age, or _Gioventute_; it is the period in which the image of Beatrice in the citadel of his mind is somewhat obscured by the tempests of passion and political turmoil, and for a while had become less paramount when her poet directed his thoughts to the service of philosophical research. Joined to the first period by the canzone addressed to the angelic movers of the sphere of Venus, it includes the greater part of the collection of lyrics (Canzoni, Bellate, Sonnets) included in the _Rime_ or _Canzoniere_; the two unfinished prose treatises which expound the mystical meaning and technical construction of these canzoni, the _Convivio_ and the _De Vulgari Eloquentia_. The three political letters connected with the Italian expedition of Henry VII. and, most probably, the special treatise in Latin prose on the Empire, the _Monarchia_, connect the second with the third period. This last period is the period of the _Divina Commedia_; the return to Beatrice, but now the allegorical Beatrice; the fulfilment of the supreme promise of the _Vita Nuova_; the result of the labours in art and philosophy which the second period had witnessed, of political experience, and of the spiritual and moral revulsion of Dante’s later years, after the bitter disillusion of the Emperor Henry’s enterprise and failure: “A fruit of sufferings excess.” To this period, subsidiary to the _Divina Commedia_, belong the letters to the Italian Cardinals, to the Florentine friend and to Can Grande, the _Quaestio de Aqua et Terra_ (if authentic), and the two _Eclogues_.