Hans [Johann] Leo Hassler [Haslerus, Haßler] was the most distinguished of the three musician sons of Isaac Hassler, organist at Nuremberg and the trown musician. With his father before him, Isaac Hassler had been settled for some time previously at Jouchunsthal in Bohemia, but had returned to Nuremberg, the original home of the family. In the funeral sermon of Isaac it is recorded of him that he had 'carefully brought up and trained his son Hans Leo in the fear of God, in the free arts, and especially in the praiseworthy art of music.' Though there were many eminent musicians at the time in Nuremberg, it does not appear that Hans Leo had any other teacher there but his father. He became very early a competent organist, as he says himself, 'ab ineunte aetate digitis quam lingua loquatior.' Nuremberg had close commercial as well as musical relations with Venice, and it may have been at the expense of the Nuremberg senate that Hans Leo in 1584 was sent to Venice for further study. Hassler was actually the first notable German composer to go to Italy to study, where in Venice he was a fellow-pupil of Giovanni Gabrieli under the latter’s uncle, Andrea Gabrieli, organist of St. Mark’s.
In 1585 Hans Leo Hassler was recalled to Germany to become private organist to Count Ottavianus (Octavian) Fugger, the great merchant prince and art patron of Augsburg, where he remained with some interruptions to the year 1600. The Augsburg years were extremely creative for him; in addition he became well-known as a composer and organist at this time, though his influence was limited because he was a Protestant in an area which was still heavily Catholic. Though his actual stay at Venice was short, he had already fully imbibed the Venetian influence in music, as the warmth and suavity of harmony of his compositions show.
Already in 1588 Frederick Lindner, the meritorious Nuremberg editor of various collections of Italian music, had includcd in one of them among the best pieces of Italian masters two motets by Hassler, 'Laudate Dominum' a 8, and 'Nuptiae factae sunt' a 12. In 1590 Hassler published on his own account 24 Italian Canzonette a 4; in 1591, Cantiones Sacrae a 4-12, originally containing 31 motets in several numbers, afterwards enlarged in 1597 to 38, including 2 Magnificats. In 1596 appeared his 'Neue teutsche Gesang nach Art der welschen Madrigalien und Canzonetten mit 4-8 Stimmen' and 'Madrigali a 5, 6. 7 & 8 voci,' this latter dedicated to Landgrave Maurice of Hesse. In 1599 Hassler published 8 masses a 4-8 dedicated to his patron Octavian Fugger. In order that he might remain in Augsburg after Octavian Fugger's death in 1600, he had applied to be appointed director of the town band, but apparently soon tired of this position, and entered into negotiations with the Nuremberg authorities to return there. For this purpose in 1601 he dedicated to the Nuremberg Senate his second great collection of motets, 'Sacri concentus' a 5-12, containing originally 48 compositions, which in the later edition of 1612 were enlarged to 56, with the further addition of 3 instrumental pieces entitled Ricercari and Canzoni a 4-8. He was appointed organist of the Frauenkirche and director of the town band at Nuremberg, but about the same time he also became absorbed in commercial speculations in connexion with the manufacture of musical clocks, which tended to divert his energies from much further musical production, and involved him in protracted legal disputes.
In 1601 appeared his 'Lustgarten neuer Teutsoher Gesäng,' containing 32 German songs a 4-8, mostly of the ballet and gagliarda type, with eleven instrumental Intradas a 6. It is in this work we find the tune 'Mein Gemiith ist mir verwirret,' in simple 5-part harmony, which in the Harmoniae sacrae (Görlitz, 1613) was first adapted to the sacred words 'Herzlicb thut mir verlangen,' and by change of rhythm has since become the familiar Passion chorale 'O Haupt voll Blut und Wunden.' In 1604 he received permission from the Nuremberg Senate to retire to Ulm, where he married and settled for a time. around this time he acquired tuberculosis, which proved to be fatal. Having some time previously been ennobled by the Emperor Rudolph, he also now received the more or less sinecure appointment of Hof-Dienerund Kammer-Organist to the Imperial court at Prague.
In 1607 Hassler published his 'Psalmen und christ.liche Gesäng mit vier stimmen auf die Melodien fugweis componirt,' This work consists of 52 settings of 30 well-known chorale melodies in the elaborate motet form. It was republished in score by Kirnberger in. 1777, with the encouragement and support of Princess Amalie of Prussia, as an example of the best contrapuntal art, but the whole work is also distinguished by its exquisite grace and expressiveness. In 1608 appeared a companion work, 'Kirchengesänge, Psalmen und geistliche Lieder auf die gemeinen Melodien mit vier Stimrnen simpliciter,er gesetzt.' This work consists of 70 settings of chorale melodies in simple note for note counterpoint, as if for congregational singing. It would seem to have continued in use in Nuremberg churches for some time afterwards, since a new edition of it was issued in 1637 with some additions by S. G. Staden. A modern edition was published in 1865 by G. W. Teschner, omitting, however, the two 8-part settings with which the original work concludes. In 1608 Hassler applied for and obtained the post of organist to the Electoral Chapel at Dresden, but in the last years of his life suffered greatly from consumption, and published no further works. In 1612 he accompanied the Elector of Saxony, Johann Georg I, to Frankfurt, where the Imperial election was to be held, and died there. After he died, Michael Praetorius and Heinrich Schütz were appointed in his place.
Nuremberg did honour to its greatest musician by a memorial epitaph in one of its churches. In 1615 Georg Gruber, a Nuremberg merchant and great lover of music, who in Venice had contracted a close friendship with both Hassler and Giovanni Gabrieli, showed honour to both by his publication, 'Reliquiae sacrorum concentuum Giovan Gabrielis, Johan-LeonisHasleri, utriusque praestantissimi musici,' etc., which contains a large number of previously unpublished compositions by both, a 4-18. Most of the works of Hassler are now available for study, of which they are well worthy, in various volumes of the Denkmäler Deutsche Tonkunst (both 1st and 2nd series). Some of the best for practical use were previously published in Proske's Musica divina; also many of Hassler's excellent settings of German chorales in Schöberlein, Schatz. The 'Lustgarten,' edited by F. Zelle, appeared in 1887 as one of Eitner's publications.
In Denkmäler Deutsche Tonkunst (2nd series), iv. 2, E. von Werra has edited from manuscript sources 16 organ works of Hassler, consisting of ricercari, canzoni, toccatas, etc., which are interesting as showing more of a chromatic tendency than his vocal works.
Hans Leo Hassler was the most eminent organist of his day. He is classed with Adam Gumpelzhaimer, Erbach, and Melchior Franck as one of the founders of German music. Hassler’s style was strongly influenced by the Gabrielis. He was one of the first to bring the innovations of the Venetian style across the Alps. While musicians of the stature of Lassus had been working in Germany for years, they represented the older school, the prima prattica, the fully developed and refined Renaissance style of polyphony; in Italy new trends were emerging which were to define what was later called the Baroque era. Musicians such as Hassler, and later Schütz, carried the concertato style, the polychoral idea, and the freely emotional expression of the Venetians into the German culture, creating the first and most Baroque development outside of Italy.
Hassler's sacred music is both for the Roman Catholic church and the Lutheran. Stylistically, his earlier music is more progressive than his later: he uses polychoral techniques, textural contrasts and occasional chromaticism in the music he wrote after coming back from Italy; but most of his later religious music is conservative, using linear polyphony in the manner of Giovanni Pierluigi da Palestrina. His secular music—madrigals, canzonette, and songs among the vocal, and ricercars, canzonas, introits and toccatas among the instrumental—show many of the advanced techniques of the Gabrielis in Italy, but with a somewhat more restrained character, and always attentive to craftsmanship and beauty of sound.