I. Warnsinck (1811-1857), Holland's first rationalist master builder Isaäc Warnsinck is the quintessential example of the nineteenth-century self-made gentleman-architect: born of an artistic and prosperous milieu in Amsterdam, he had, through private education, 'mastered those sciences which characterize the true architect' and completed several study trips and 'grand tours' through Europe. Although Warnsinck has remained underexposed in contemporary literature, he was among the first professional architects in the Netherlands and was an authoritative public figure. Warnsinck was involved in the founding of the "Maatschappij tot Bevordering der Bouwkunst" in 1842 and regularly used the "Bouwkundig Bijdragen," the Maatschappij's equally new journal, as a mouthpiece for his ideas and criticism. As such, Warnsinck was deeply concerned with the level of architectural practice in the Netherlands. On the eve of the founding of the Society in December 1841, he and A.W. van Dam and E.S. Heyninckx had even written a letter to the Minister of the Interior in which they proposed, among other things, the establishment of an education for architects to raise the level of architecture in the Netherlands. They also wanted to appoint building commissions to review designs for government buildings, and believed that the architectural profession should be protected. Warnsinck also contributed greatly to the substantive architectural debate in the Netherlands in the period 1840-1860. As far as is known, he was the first to make the link between truth and character in an 1840 brochure on Zocher's design of the Stock Exchange in Amsterdam. Although he did not explicitly write about truth in it, the rational use of construction and building materials played an important role in his argument. For Warnsinck, there was a connection between the external appearance, function and construction of a building. Moreover, in 1843, in the "Bouwkundige Bijdragen," he made a plea for the rational use of brick. He denounced the practice common at the time of imitating Greek forms in wood, brick and piece: 'a pseudo-Greek mask architecture' (Warnsinck 1843, p. 129). In so doing, he introduced in the 1840s a principle that would be claimed as "Gothic rationalism" only fifteen years later by P.J.H. Cuypers and J.A. Alberdingk Thijm. Warnsinck opposed the proliferation of forms and motifs borrowed from different styles and the arbitrary imitation of every conceivable architectural style: Munich provides a remarkable example of this; in that city, where now, of all other known cities, the arts, and especially architecture, flourish the most, one finds Ancient Greek, Roman, Byzantine, Lombard, Romanesque, Florentine, Gothic and Palladian buildings, which, although their execution leaves nothing to be desired, nevertheless give to the whole a colorful and indefinable appearance and character (Warnsinck 1840, p.18). Thus, according to him, architects had to understand building styles, find out the underlying principles and rules, trace the original function of parts, motifs and forms, so that they could be applied in the right way, adapted to the building task and the requirements of their own time. In the 'Preface' to the first edition of the Architectural Contributions, Warnsinck wrote: 'Whoever, therefore, with any hope of success, wishes to make use of architectural parts and components, should know their meaning, purpose, origin and development; whoever lacks this knowledge, resembles a physician, who prescribes remedies, the nature, strength and effect of which are unknown to him, or in other words, a quack' (Warnsinck 1842, p. vi). According to Warnsinck, architectural history could be helpful in finding truth of right character. One example he cited was the chancellery in Leeuwarden, which he believed had character and truth and in which "the interior must also have matched the exterior" (Krabbe 1998, pp. 185, 186 and 198, and Warnsinck 1852, p. 89). For the Amsterdam Merchant's Exchange he had the round-arched style in mind, because the use of round arches was inherent in the building material brick; above the windows relief arches had to be applied, where in natural stone straight frames could be used (Krabbe 1998, p. 190). Warnsinck had come to know this style through the German architects H. Hübsch (in the southern German state of Baden) and K.F. Schinkel (in Berlin), whose work he had been shown around Berlin in 1838 by L. Persius, one of Schinkel's most gifted pupils. In the Netherlands, he was one of the first architects to apply this style, doing so at the 1840 church in Wilhelminadorp. In the following two decades, the round-arched style became a favored option for Dutch architects. Warnsinck's office practice falls into two parallel spheres of commissioning. After establishing himself as an architect in Amsterdam in 1838, he received numerous private commissions. These included two country houses near Haarlem and the new construction of the Reformed Church in Gorinchem, in collaboration with his assistant A.N. Godefroy. From 1845 he also worked as an architect-advisor to the Ministry of Justice. Indeed, under the influence of American ideas, the so-called cellular system was introduced in the outdated Dutch prison system in the 1840s, confronting the government with an unprecedented building task. The government made grateful use of Warnsinck's experience and built prisons in Amsterdam, Utrecht and numerous smaller municipalities, among others. Here, in contrast to his private commissions, Warnsinck practiced extreme austerity and employed flat brick facades closed by simple guttering. Warnsinck continued to combine his work as an architect with social functions until his death in 1857. Thus, from 1848 he was secretary of the fourth class (fine) arts of the Royal Institute of Sciences, Letters and Fine Arts, became a member of the Amsterdam city council in 1851, and was even alderman of Public Works in his hometown from 1855 to 1857. Education: Lessons in physics and mechanics J. Jonkhert/1825;theoretical subjects J. de Greef/after 1825;practical training J. Jansen/after 1825 Additional activities: Royal Academy of Fine Arts/member board of directors/1840-1857;Maatschappij tot Bevordering der Bouwkunst/secretary/1841-1857;Architectura et Amicitia/ honorary member/1855-1857;Royal Institute of Sciences, Letters and Fine Arts/secretary of the fourth class (fine arts)/1848-1857;Amsterdam city council/member/1851-1855;Public Works Amsterdam/ alderman/1855-1857