HEINSIUS, NIKOLAES (1620-1681), Dutch scholar, son of Daniel Heinsius, was born at Leyden on July 20, 1620. His boyish Latin poem of Breda expugnata was printed in 1637, and attracted much attention. In 1642 he began his wanderings with a visit to England in search of mss. of the classics. From 1644 to 1653 he travelled without cessation between the principal libraries of Europe, everywhere collating mss. and taking philological and textual notes. He collected his Latin poems into a volume in 1653. His latest labours were the editing of Velleius Paterculus in 1678, and of Valerius Flaccus in 1680. He died at The Hague on Oct. 7, 1681. Nikolaes Heinsius was one of the purest and most elegant of Latinists, and if his scholarship was not quite so perfect as that of his father, he displayed higher gifts as an original writer.