e shifting light upon the
landscape. He generally sketched whatever he thought beautiful or
striking, marking every tinge of light with a similar colour; from these
sketches he perfected his landscapes. Leaving Tassi, he made a tour in
Italy, France and a part of Germany, including his native Lorraine,
suffering numerous misadventures by the way. Karl Dervent, painter to
the duke of Lorraine, kept him as assistant for a year; and he painted
at Nancy the architectural subjects on the ceiling of the Carmelite
church. He did not, however, relish this employment, and in 1627
returned to Rome. Here, painting two landscapes for Cardinal
Bentivoglio, he earned the protection of Pope Urban VIII, and from about
1637 he rapidly rose into celebrity. Claude was acquainted not only with
the facts, but also with the laws of nature; and the German painter
Joachim von Sandrart relates that he used to explain, as they walked
together through the fields, the causes of the different appearances of
the same landscape at different hours of the day, from the reflections
or refractions of light, or from the morning and evening dews or
vapours, with all the precision of a natural philosopher. He elaborated
his pictures with great care; and if any performance fell short of his
ideal, he altered, erased and repainted it several times over.

His skies are aerial and full of lustre, and every object harmoniously
illumined. His distances and colouring are delicate, and his tints have
a sweetness and variety till then unexampled. He frequently gave an
uncommon tenderness to his finished trees by glazing. His figures,
however, are very indifferent; but he was so conscious of his deficiency
in this respect, that he usually engaged other artists to paint them for
him, among whom were Courtois and Filippo Lauri. Indeed, he was wont to
say that he sold his landscapes and gave away his figures. In order to
avoid a repetition of the same subject, and also to detect the very
numerous spurious copies of his works, he made tinted outline drawings
(in six paper books prepared for this purpose) of all those pictures
which were transmitted to different countries; and on the back of each
drawing he wrote the name of the purchaser. These books he named _Libri
di verita_. This valuable work (now belonging to the duke of Devonshire)
has been engraved and published, and has always been highly esteemed by
students of the art of landscape. Claude, who had suffered much