King of Portugal João IV

João IV of Portugal (Vila Viçosa, 19 March 1604 – Lisbon, 6 November 1656) was King of Portugal and one of the most singular figures in Iberian music of the seventeenth century. Although his training and interests were above all musical, his political role is inseparable from his biography: following the revolt of 1640 against Spanish rule, he was elected sovereign of the country.

As heir to the Duchy of Bragança, whose family was noted for its love of music, he received a musical education. His first teacher was Robert Tornar, an English or possibly Irish composer who had been a pupil of Gery de Ghersem and Mathieu Rosmarin at the Flemish Royal Chapel in Madrid. His reign was marked by intermittent war with Spain and by diplomacy, although the monarch showed little interest in politics and devoted his energy to music: he supported composers and institutions within his domains and maintained a constant association with leading musicians.

João IV assembled the largest musical library of his time, based on the holdings of the ducal library of his father and grandfather. Much of his treasure was lost in the earthquake and fire of Lisbon in 1755, although the catalogue printed in 1649 makes it possible to reconstruct a good part of the collection. Only the first volume of a broader project was published, but its 521 pages describe hundreds of volumes of masses, motets, magnificats, psalms, madrigals, villancicos and instrumental prints, as well as more than 2,000 printed editions and 4,000 manuscript compositions, from the early sixteenth century to the late 1640s. It is considered certain that this catalogue records less than a third of the library's total contents at the time of his death. It is also an essential source for understanding European music printing and the conventions of religious polyphony in the Iberian Peninsula.

As a writer, he is known for two brief publications: a defence of the expressive power of the stile antico and a response to criticisms of a Mass by Palestrina. Both appeared without place, date or authorship, in Spanish and Italian, although the preliminary sonnets reveal his actual name through acrostics. His polemical defence of modern music upheld the purity of the polyphony of Palestrina, Victoria and their contemporaries, though with arguments that were not always consistent. Two manuscript treatises in Portuguese that earlier authors attributed to him have been lost, perhaps destroyed together with his library.

He was, by far, the greatest individual patron of music and musicians in seventeenth-century Portugal. He sponsored the publication of polyphonic works by Duarte Lobo in Antwerp and by João Lourenço Rebelo in Rome, as well as several volumes by Manuel Cardoso and Filipe de Magalhães printed in Lisbon. His protection was also decisive in the careers of Spanish composers such as Carlos Patiño and Mathieu Rosmarin. He composed little: only two brief motets for four voices survive complete, attributed to him as early as the mid-eighteenth century, written in the stile antico and proclaiming his devotion to the style of Palestrina.