Oecolampadius, John (Johann Hussgen) (1482–1531)
German theologian and reformer
Oecolampadius was born at Weinsberg, at that time in the
Palatinate. After visiting Bologna, he studied theology at
Heidelberg and in 1515 was appointed preacher at Basle
cathedral, where his strong reforming tendencies became
plain. In 1520 he published a Greek grammar and was in-
vited to preach in Augsburg, but a period of doubt then
caused him to withdraw for a time to a monastery. In
1522, his reforming faith restored, he moved to Ebern-
burg, and then returned to Basle where he spent the rest of
his life as a leader among the reformers. In 1528 he mar-
ried, and the same year he and Ulrich ZWINGLIcaused the
reformed faith to be adopted at Berne and the Mass to be
discontinued at Basle. In 1529 he attended the Colloquy
of MARBURG.
Okeghem, Jean de See OCKEGHEM, JOHANNES
Oldenbarneveldt, Johan van (1547–1619) Dutch
statesman
Oldenbarneveldt was born at Amersfoort. He studied law
at Louvain, Bourges, and Heidelberg, where he became a
Protestant, and in 1568 he supported the revolt against
Spain. In 1579 he joined WILLIAM THE SILENT, Prince of
Orange, in negotiating the Union of Utrecht, which united
the northern provinces of the Netherlands. He was
attorney-general of the union and secretary to the provin-
cial estates of Holland. After the assassination of William
the Silent in 1584, he took charge of domestic and foreign
affairs, while Prince MAURICE OF NASSAUcommanded the
armed forces. He negotiated an alliance with France and
England in 1596 and a controversial 12-year truce with
Spain in 1609. He worked to maintain the dominance of
the province of Holland within the union and in religious
affairs supported the Arminians (see ARMINIANISM) against
the Calvinists; this brought him into conflict with Mau-
rice. Accused of subverting church and state, he was be-
headed at The Hague.
Further reading: Jan den Tex, Oldenbarnevelt, transl.
R. B. Powell, 2 vols (Cambridge, U.K.: Cambridge Univer-
sity Press, 1973).
Oliver, Isaac (c. 1560–1617) English painter
Born in Rouen, the son of French Huguenots, Oliver was
brought to England in 1568 and studied painting under
Nicholas HILLIARD. Although he also painted life-size por-
traits and religious and classical scenes, Oliver is remem-
bered chiefly as a painter of miniature portraits. He
traveled in the Netherlands (1588) and to Venice (1596)
and by 1595 he had become Hilliard’s chief rival. Oliver’s
patrons included Anne of Denmark (1604) and later
Henry Frederick, Prince of Wales, of whom he painted a
striking portrait miniature (c. 1610). The large-scale
equestrian portrait of the prince in the Venetian manner,
formerly attributed to Oliver, is now assigned to Robert
Peake. In his later years Oliver adopted a more naturalis-
tic style and painted historical and biblical scenes in the
mannerist tradition. His son Peter (1594–1647) also ex-
ecuted paintings in his father’s later style.Olivetan (Pierre Robert) (c. 1506–1538) French
Protestant reformer and translator
Born at Noyon, Picardy, a cousin of John CALVIN, Olivetan
was forced to abandon his studies at Orleans and flee to
Strasbourg after his conversion to Protestantism. He be-
came actively involved in the Reformation, preaching to
the Waldenses in Piedmont, and undertook the translation
of the Bible into French; this was published at Serrières,
near Neuchâtel, in 1535. Extensively revised by Calvin
and others during the 16th century, Olivetan’s Bible
ranked with that of LEFÈVRE D’ÉTAPLESas a major source
for subsequent French translations of the Scriptures.Ollanda, Francisco d’ See FRANCISCO DA HOLLANDAO’Malley, Grace (Gráinne Ni Mháille) (c. 1530–
c. 1603) Irish sea queen and nationalist leader
A scion of the hereditary chieftains of the Barony of Mur-
risk, she held sway with her first husband, Donal O’Fla-
herty, at Bunowen Castle, County Galway. After his death
in clan fighting she took control of his ships and preyed
on British vessels along the Scottish coast. Around 1566
she married the clan chief Richard Burke of Mayo, and be-
came an important local powerbroker during the years of
revolt against English control. Widowed once again
(1586), she was captured at her Clew Bay castle by British
forces intent on suppressing her piracy in the Aran Is-
lands. She was taken to Dublin to be hanged, but freed on
her son-in-law’s intercession. When the English fleet at-
tacked Clew Bay (c. 1592) she fled to Ulster. In 1593 she
sailed to England and petitioned Elizabeth I for restora-
tion of her husband’s estates; these were handed over, not
to her, but to her son Theobald. At age 70 she was still
leading attacks on ships of other Irish clans that strayed
into O’Malley waters.optics Considerable advances were made in antiquity in
the study of geometrical optics. Ancient scientists distin-
guished between “catoptrics”, the study of reflection, and
“dioptrics”, the corresponding study of refraction. While
they had managed to formulate the basic laws of reflection
they were less successful in their work on refraction.
Ptolemy had established no more than that the angle of in-
cidence was always greater than the angle of refraction,
whatever the media. It was not until the early 17th cen-
tury that Willebrord SNELLestablished the true relation-
ship. The ratio of the sines of the angles of incidence and
refraction, he demonstrated, were constant for any media.ooppttiiccss 3 34477